EP0709724B1

EP0709724B1 - Silver halide emulsions with doped epitaxy

Info

Publication number: EP0709724B1
Application number: EP95202609A
Authority: EP
Inventors: Eric Leslie c/o EASTMAN KODAK COMPANY Bell; Traci Y. c/o Eastman Kodak Company Kuromoto; Robert Don C/O Eastman Kodak Company Wilson; Woodrow Gordon C/O Eastman Kodak Company Mcdugle; Raymond Stanley c/o Eastman Kodak Company Eachus; Sherrill Austin Eastman Kodak Company Puckett; Myra Toffolon C/O Eastman Kodak Company Olm
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1994-09-30
Filing date: 1995-09-28
Publication date: 2002-05-08
Anticipated expiration: 2015-09-28
Also published as: EP0709724A2; EP0709724A3; DE69526624D1; JPH08179452A; DE69526624T2

Description

The invention relates to photography. More specifically, the invention relates to photographic silver halide emulsions and to processes for their preparation.
All references to periods and groups within the periodic table of elements are based on the format of the periodic table adopted by the American Chemical Society and published in the Chemical and Engineering News, Feb. 4, 1985, p. 26. In this form the prior numbering of the periods was retained, but the Roman numeral numbering of groups and the A and B group designations (having opposite meanings in the U.S. and Europe) were replaced by a simple left to right 1 through 18 numbering of the groups.
The term "dopant" is employed herein to designate any element or ion other than silver or halide incorporated in a face centered silver halide crystal lattice.
The term "metal" in referring to elements includes all elements other than those of the following atomic numbers: 2, 5-10, 14-18, 33-36, 52-54, 85 and 86.
The term."Group VIII metal" refers to an element from period 4, 5 or 6 and any one of groups 8 to 10 inclusive.
The term "Group VIII noble metal" refers to an element from period 5 or 6 and any one of groups 8 to 10 inclusive.
The term "palladium triad metal" refers to an element from period 5 and any one of groups 8 to 10 inclusive.
The term "platinum triad metal" refers to an element from period 6 and any one of groups 8 to 10 inclusive.
The term "halide" is employed in its conventional usage in silver halide photography to indicate chloride, bromide or iodide.
In referring to silver halide grains containing two or more halides, the halides are named in their order of ascending concentrations.
The term "pseudohalide" refers to groups known to approximate the properties of halides--that is, monovalent anionic groups sufficiently electronegative to exhibit a positive Hammett sigma value at least equaling that of a halide--e.g., CN^-, OCN^-, SCN^-, SeCN^-, TeCN^-, N₃ ^-, C(CN)₃ ^- and CH^-.
The term "C-C, H-C or C-N-H organic" refers to groups that contain at least one carbon-to-carbon bond, at least one carbon-to-hydrogen bond or at least one carbon-to-nitrogen-to-hydrogen bond sequence.
The term "epitaxial deposition" refers to crystal growth onto a substrate of a detectibly different crystal structure wherein the substrate controls the crystalline orientation of the crystal growth. Since each silver halide forms a crystal structure that is either different in kind or in unit cell dimensions from the remaining silver halides, detectable differences in halide composition of the substrate and oriented crystal growth satisfy the "different crystal structure" requirement to qualify as epitaxial deposition. The term "epitaxy" is employed to indicate the crystal growth epitaxially deposited.
To avoid repetition, it is understood that all references to photographic emulsions are to negative-working photographic emulsions, except as otherwise indicated.
Research Disclosure is published by Kenneth Mason Publications, Ltd., Dudley House, 12 North St., Emsworth, Hampshire P010 7DQ, England
Research Disclosure, Vol. 176, December 1978, Item 17643, Section I, sub-section A, states that "sensitizing compounds, such as compounds of copper, thallium, lead, bismuth, cadmium and Group VIII noble metals, can be present during precipitation of silver halide" emulsions. The quoted passage is followed by citations to demonstrate the general knowledge of the art that metals incorporated as dopants in silver halide grains during precipitation are capable of acting to improve grain sensitivity.
Research Disclosure, Vol. 308, December 1989, Item 308119, Section I, sub-section D, states that "compounds of metals such as copper, thallium, lead, mercury, bismuth, zinc, cadmium, rhenium, and Group VIII metals (e.g., iron, ruthenium, rhodium, palladium, osmium, iridium and platinum) can be present during the precipitation of silver halide" emulsions. The quoted passage is essentially cumulative with Research Disclosure 17643, Section I, sub-section A, except that the metals have been broadened beyond sensitizers to include those that otherwise modify photographic performance when included as dopants during silver halide precipitation.
Research Disclosure 308119, sub-section D, proceeds further to point out a fundamental change that occurred in the art between the 1978 and 1989 publication dates of these silver halide photography surveys. Research Disclosure 308118, I-D states further:
The metals introduced during grain nucleation and/or growth can enter the grains as dopants to modify photographic properties, depending on their level and location within the grains. When the metal forms a part of a coordination complex, such as a hexacoordination complex or a tetracoordination complex, the ligands can also be occluded within the grains. Coordination ligands, such as halo, aquo, cyano, cyanate, thiocyanate, nitrosyl, thionitrosyl, oxo, and carbonyl ligands are contemplated and can be relied upon to vary emulsion properties further.
Research Disclosure, Vol. 365, Sept. 1994, Item 36544, Section I, sub-section D, paragraphs (3), (4) and (5), are considered cumulative with Research Disclosure Item 308119.
Although it was known for many years that the photographic performance of silver halide emulsions can be modified by the introduction of dopant metal ions during grain precipitation, it was generally assumed that the anion paired with the metal ion, except when it happened to be a halide ion, did not enter the grain structure and that the counterion selection was unrelated to photographic performance. Janusonis et al U.S. Patent 4,835,093; McDugle et al U.S. Patents 4,933,272, 4,981,781 and 5,037,732; Marchetti et al U.S. Patent 4,937,180; and Keevert et al U.S. Patent 4,945,035 were the first to demonstrate that ligands capable of forming coordination complexes with dopant metal ions are capable of entering the grain crystal structure and producing modifications of photographic performance that are not realized by incorporation of the transition metal ion alone. In each of these patents emphasis is placed on the fact that the coordination complex steric configuration allows the metal ion in the complex to replace a silver ion in the crystal lattice with the ligands replacing adjacent halide ions.
Thereafter, by hindsight, it was realized that earlier disclosures of the addition of dopant metal ions, either as simple salts or as coordination complexes, had inadvertently disclosed useful ligand incorporations. Of these inadvertent teachings, the incorporation of iron hexacyanide during grain precipitation is the most notable and is illustrated by Shiba et al U.S. Patent 3,790,390; Ohkubo et al U.S. Patent 3,890,154; Iwaosa et al U.S. Patent 3,901,711 and Habu et al U.S. Patent 4,173,483.
Ohya et al European patent application 0 513 748 A1, published Nov. 19, 1992, discloses photographic silver halide emulsions precipitated in the presence of a metal complex having an oxidation potential of from -1.34 V to +1.66 V and a reduction potential not higher than -1.34 V and chemically sensitized in the presence of a gold-containing compound. On page 2 of the patent a table of illustrative complexes satisfying the oxidation and reduction potentials are listed. This listing includes, in addition to the complexes consisting of halide and pseudohalide ligands, K₂[Fe(EDTA)], where EDTA is an acronym for ethylenediaminetetraacetic acid. In a preferred variation it is taught to employ in combination with a required metal complex an iridium containing compound. Examples of useful iridium compounds include, in addition to simple halide salts and coordination complexes containing halide ligands, hexaamine iridium (III) salt (i.e., a [(NH₃)₆Ir]⁺³ salt), hexaamine iridium (IV) salt (i.e., a [(NH₃)₆Ir]⁺⁴ salt), a trioxalate iridium (III) salt and a trioxalate iridium (IV) salt. While offering a somewhat broader selection of ligands for use with the metals disclosed, Ohya et al does not attach any importance to ligand selection and does not address whether ligands are or are not incorporated into the grain structures during precipitation.
Ohkubo et al U.S. Patent 3,672,901 (hereinafter designated Ohkubo et al '901) discloses silver halide precipitation in the presence of iron compounds. Ohkubo et al states, "Specific examples include: ferrous arsenate, ferrous bromide, ferrous carbonate, ferrous chloride, ferrous citrate, ferrous fluoride, ferrous formate, ferrous gluconate, ferrous hydroxide, ferrous iodide, ferrous lactate, ferrous oxalate, ferrous phosphate, ferrous succinate, ferrous sulfate, ferrous thiocyanate, ferrous nitrate, ammonium ferrous sulfate, potassium hexacyanoferrate (II), potassium pentacyanoamine-ferrate (II), basic ferric acetate, ferric albuminate, ammonium ferric acetate, ferric bromide, ferric chloride, ferric chromate, ferric citrate, ferric fluoride, ferric formate, ferric glycero phosphate, ferric hydroxide, acidic ferric phosphate, sodium ferric ethylenedinitrilotetraacetate, sodium ferric pyrophosphate, ferric thiocyanate, ferric sulfate, ammonium ferric sulfate, guanidine ferric sulfate, ammonium ferric citrate, potassium hexacyanoferrate (III), tris(dipyridyl) iron (III) chloride, potassium ferric pentacyanonitrosyl, and hexaurea iron (III) chloride. The only compounds reported in the Examples are hexacyanoferrate (II) and (III) and ferric thiocyanate.
Hayashi U.S. Patent 5,112,732 discloses useful results to be obtained in internal latent image forming direct positive emulsions precipitated in the presence of potassium ferrocyanide, potassium ferricyanide or an EDTA iron complex salt. Doping with iron oxalate is demonstrated to be ineffective.
While the art noted above has heretofore achieved useful photographic performance modifications through adding dopant metal salts and coordination complexes during grain precipitation, the photographic effects that have heretofore been achieved have been attributable to the dopant metal alone or to the metal dopant in combination with coordination complex ligands chosen from only a few restricted categories: halo, pseudohalo, aquo, nitrosyl, thionitrosyl, carbonyl and oxo ligands.
Prior to the present invention reported introductions during grain precipitation of metal coordination complexes containing organic ligands have not demonstrated photographically useful modifying effects attributable to the presence of the organic ligands, and, in fact, such coordination complexes have limited the photographic modifications that would be expected from introducing the metal in the form of a simple salt. Performance modification failures employing ethylenediamine and trioxalate metal coordination complexes of types analogous to those suggested by Ohya et al and Ohkubo et al '901 are presented below as comparative Examples.
Bigelow U.S. Patent 4,092,171 discloses the use of tetracoordination complexes of platinum and palladium with organophosphine ligands to be useful chemical sensitizers. The relationship of tetracoordination complexes to silver halide crystal structures is fundamentally different than that of hexacoordination complexes in that tetracoordination complexes, if they are incorporated, occupy intersticial sites within the crystal lattice rather than substitutionally displacing silver and halide ions in the manner of the hexacoordination metal complexes.
Photographic emulsions containing composite grains comprised of host grain portions and surface portions epitaxially deposited on the host grain portions are well known in the art. An illustrative listing of emulsions containing composite grains appears in Research Disclosure, Vol. 365, Sept. 1994, Item 36544, I. Emulsion grains and their preparation, A. Grain halide composition, paragraph (5).
Prior filed, non-prepublished EP-A-0634689 discloses internally doped silver halide emulsions containing a metal hexacoordination complex having at least one organic ligand containing at least one carbon-to-carbon bond, at least one carbon-to-hydrogen bond or at least one carbon-to-nitrogen-to-hydrogen bond sequence and at least half of the metal coordination sites occupied by halide or pseudohalide ligands. The G-Series examples thereof disclose composite silver halide grains including cubic silver chloride host grain portions, and epitaxially deposited silver bromide surface portions which include K₂[IrCl₅(pyrazine)] or K₄[Ir₂Cl₁₀(pyrazine)] on the cubic silver chloride host grain portions.
The present invention has for the first time introduced during epitaxial deposition dopant metal hexacoordination complexes containing one or more organic ligands, other than for the epitaxially deposited silver bromide which includes K₂[IrCl₅(pyrazine)] or K₄[Ir₂Cl₁₀(pyrazine)] on cubic silver chloride host grain portions disclosed in EP-A-0634689, and obtained modifications in photographic performance that can be attributed specifically to the presence of the organic ligand or ligands. The result is to provide the art with additional and useful means for tailoring photographic performance to meet specific application requirements.
In one aspect this invention is directed to a photographic silver halide emulsion comprised of radiation sensitive composite silver halide grains including host grain portions accounting for at least 50 percent of total silver and surface portions epitaxially deposited on the host grain portions characterized in that the epitaxially deposited surface portions on the host grain portions exhibit a face centered cubic crystal lattice structure containing a hexacoordination complex of a metal from periods 4, 5 and 6 of groups 3 to 14 inclusive of the periodic table of elements in which one or more organic ligands each containing at least one carbon-to-carbon bond, at least one carbon-to-hydrogen bond or at least one carbon-to-nitrogen-to-hydrogen bond sequence occupy up to half the metal coordination sites in the coordination complex and at least half of the metal coordination sites in the coordination complex are provided by halogen or pseudohalogen ligands, with the proviso that when the host grain portions comprise cubic silver chloride grains, the hexacoordination complex of a metal contained in the epitaxially deposited surface portion is other than K₂[IrCl₅(pyrazine)] or K₄[Ir₂Cl₁₀(pyrazine)].
The present invention is directed toward the improvement of photographic silver halide emulsions comprised of radiation sensitive composite silver halide grains. The composite grains are formed by epitaxially depositing surface portions onto a host grain population. The host grain portions account for at least 50 percent (preferably at least 90 percent) of the total silver forming the composite grains. The epitaxially deposited surface portions of the composite grains can form a shell, but are preferably nonuniformly distributed on the host grains. In a specific preferred form the epitaxially deposited surface portions are located principally adjacent at least one of the edges and corners of the host grains.
The host grains can be chosen of any convenient conventional silver halide composition. Maskasky U.S. Patent 4,094,684 discloses composite grains in which silver iodide host grains serve as substrates for the epitaxial deposition of silver chloride. However, it is preferred that the host grain portions and required that the epitaxially deposited grain surface portions be selected from among those individual and mixed silver halides that form a face centered cubic crystal lattice structure, such as silver chloride, silver bromide, silver chlorobromide, silver bromochloride, silver iodobromide, silver iodochloride, silver iodochlorobromide and silver iodobromochloride.
To qualify definitionally as epitaxy the surface portions of the grains must exhibit a detectibly different crystal lattice structure than the host portions of the grains. This is most conveniently satisfied by employing different halide compositions in precipitating the host and surface portions of the grains. Thus, the composite grains can take any of the varied forms disclosed by Maskasky U.S. Patents 4,435,501, 4,463,087 and 5,275,930, Ogawa et al U.S. Patent 4,735,894, Yamashita et al U.S. Patent 5,011,767, Haugh et al U.K. Patent 2,038,792, Koitabashi EPO 0 019 917, Ohya et al EPO 0 323 215, Takada EPO 0 434 012, Chen EPO 0 498 302 and Berry and Skillman, "Surface Structures and Epitaxial Growths on AgBr Microcrystals", Journal of Applied Physics, Vol. 35, No. 7, July 1964, pp. 2165-2169.
In one specifically preferred form of the invention the host grains are formed of silver bromide or iodobromide and the epitaxially deposited surface portions are formed by the precipitation of silver chloride. By relying on either the iodide level in the host grains or an adsorbed site director the silver chloride can then be sited at the edges or corners of the host grains. Corner epitaxy produces higher speed composite grains than edge epitaxy and much higher speed composite grains than simply shelling the host grains. Maskasky U.S. Patents 4,435,501 and 4,463,087, cited above, disclose tabular and nontabular composite grains, respectively, of this preferred form.
In another preferred form the emulsions of this invention contain high (at least 90 mole percent) chloride grains and contain from 0 to 10 mole percent bromide and from 0 to 2 mole percent iodide. Preferably the composite grains contain at least 0.5 mole percent bromide. The host portion of the grains can consist essentially of silver chloride. The epitaxially deposited surface portions of the grains contain a higher proportion of halides other than chloride than the host grains. Preferably the surface portions of the grains contain a higher proportion of bromide than the host portions of the grains. Composite grains containing higher portions of the halides other than chloride in the surface portions of the grains are illustrated by Tanaka EPO 0 080 905, Hasebe et al U.S. Patent 4,865,962, Asami EPO 0 295 439, Suzumoto et al U.S. Patent 5,252,454, Ohshima et al U.S. Patent 5,252,456, and Maskasky U.S. Patent 5,275,930.
The present invention has achieved modifications of photographic performance that can be specifically attributed to the presence of metal coordination complexes containing one or more C-C, H-C or C-N-H organic ligands during the epitaxial deposition portion of composite grain precipitation. The photographic effectiveness of these C-C, H-C or C-N-H organic ligand metal complexes is attributed to the recognition of criteria for selection never previously appreciated by those skilled in the art. Location of the complexes in epitaxially formed surface portions of composite grains has been observed to be a favored location.
The complexes are chosen from among hexacoordination complexes to favor steric compatibility with the face centered cubic crystal structures of silver halide grains. Metals from periods 4, 5 and 6 and groups 3 to 14 inclusive of the periodic table of elements are known to form hexacoordination complexes and are therefore specifically contemplated. Preferred metals for inclusion in the coordination complexes are Group VIII metals. Non-noble Group VIII metals (i.e., the period 4 Group VIII metals) are contemplated for grain incorporation, with iron being a specifically preferred dopant metal. Noble Group VIII metals (those from the palladium and platinum triads) are contemplated, with ruthenium and rhodium being specifically preferred period 5 metal dopants and iridium being a specifically preferred period 6 dopant.
Further defining the coordination complexes are the ligands they contain. The coordination complexes contain a balance of halide and/or pseudohalide ligands (that is, ligands of types well known to be useful in photography) and C-C, H-C or C-N-H organic ligands. To achieve performance modification attributable to the presence of the C-C, H-C or C-N-H organic ligands at least half of the coordination sites provided by the metal ions must be satisfied by pseudohalide, halide or a combination of halide and pseudohalide ligands and at least one of the coordination sites of the metal ion must be occupied by an organic ligand. When the organic ligands occupy all or even the majority of coordination sites in the complex, photographic modifications attributable to the presence of the organic ligand have not been identified.
A surprising discovery has been that the selection of the organic ligands is not limited by steric considerations in the manner indicated by Janusonis et al, McDugle et al, Marchetti et al and Keevert et al, all cited above. Whereas each of these patents teach replacing a single halide ion the crystal lattice structure with a nonhalide ligand occupying exactly the same lattice position, C-C, H-C or C-N-H organic ligands of varied steric configurations have been observed to be effective. While it seems plausible that the smaller of these organic ligands lend themselves to one-for-one displacement of halide ions in the crystal lattice structure, the demonstration of the effectiveness of larger organic ligands and C-C, H-C or C-N-H organic ligands of varied steric forms clearly demonstrates a much broader tolerance for geometrical configuration divergence of the host face centered cubic crystal lattice structure and the ligands of the metal dopant coordination complexes than had heretofore been thought feasible. In fact, the variation of steric forms of C-C, H-C or C-N-H organic ligands observed has led to the conclusion that neither the steric form nor size of the C-C, H-C or C-N-H organic ligand is in itself a determinant of photographic utility.
Metal hexacoordination complexes suitable for use in the practice of this invention have at least one C-C, H-C or C-N-H organic ligand and at least half of the metal coordination sites occupied by halide or pseudohalide ligands. A variety of such complexes are known. The specific embodiments are listed below. Formula acronyms are defined at their first occurrence. MC-1
[Sc(NCS)₃(py)₃]
py = pyridine
Tris (pyridine) tris (thiocyanato) scandium (III) Reported by G. Wilkinson, R.D. Gillard and J.A. McCleverty (eds.), Comprehensive Coordination Chemistry, Pergamon 1987. MC-2
[M(Cl₃)(1,10-phenanthroline) (H₂O)]
M = La, Ce, Pr, Nd, Sa
Aquotrichloro(1,10-phenanthroline) lanthanide (III) Reported by F. A. Hart and F. P. Laming, J. Inorg. Nucl. Chem., 26, 579 (1964). MC-3
(Et₄N) [TiCl₄(MeCN)₂]
Et = ethyl, Me = methyl
Tetraethylammonium bis(acetonitrile) tetrachloro titanium (III) Reported by B. T. Russ and G. W. A. Fowles, Chem.Comm., 1, 19 (1966). MC-4
(R₄N)[TiCl₄(EtO)(MeCN)]
EtO = CH₃CH₂O MC-4a R = Me
Tetramethylammonium (acetonitrile) ethoxytetrachloro titanate (IV) MC-4b R = Et
Tetraethylammonium (acetonitrile) ethoxytetrachloro titanate (IV) a-b Reported by F. Von Adalbert, Z. Anorg. Allgem. Chem., 338, 147 (1965). MC-5
(Et₄N) [TiCl₅(MeCN)]
Tetraethylammonium (acetonitrile) pentachloro titanate (IV) Reported by J. M. Kolthoff and F. G. Thomas, J. Electrochem. Soc., 111, 1065 (1964). MC-6
Pyridinium [V(NCS)₄(py)₂]
Pyridinium bis (pyridine) tetra(thiocyanato) vanadate (III) Reported by R. J. H. Clark, Comprehensive Inorganic Chemistry, Vol. 3, pp. 544-545, edited by A. F. Trotman-Dickerson, Pergoman Press, Oxford, 1973. MC-7
(Et₄N) [VCl₄(MeCN)₂]
Tetraethylammonium bis(acetonitrile) tetrachloro vanadate (III) Reported by R. J. H. Clark, Comprehensive Inorganic Chemistry, Vol. 3, pp. 544-545, edited by A. F. Trotman-Dickerson, Pergoman Press, Oxford, 1973. MC-8
[WCl₄(en)]
en = ethylenediamine
(Ethylenediamine)tetrachloro tungsten (IV) Reported by C. D. Kennedy and R. D. Peacock, J. Chem. Soc., 3392 (1963). MC-9
(Bu₄N)[Cr(NCO)₄(en)]
Bu = butyl
Tetrabutylammonium (ethylenediamine) tetra(cyanato) chromate (III) Reported by E. Blasius and G. Klemm, Z. Anorg. Allgem. Chem., 428, 254 (1977). MC-10
(Bu₄N) [Cr(NCO)₄(1,2-propanediamine)]
Tetrabutylammonium tetra (cyanato) - (1,2-propanediamine) chromate (III) Reported by E. Blasius and G. Klemm, Z. Anorg. Allgem. Chem., 443, 265 (1978). MC-11
(Bu₄N) [Cr(NCO)₄(1,2-cyclohexanediamine)]
Tetrabutylammonium tetra (cyanato) - (1,2-cyclohexanediamine) chromate (III) Reported by E. Blasius and G. Klemm, Z. Anorg. Allgem. Chem., 443, 265 (1978). MC-12
[ReOCl₃(en)]
Trichloro(ethylenediamine)oxo rhenium (V) Reported by D. E. Grove and G. Wilkinson, J. Chem. Soc.(A), 1224 (1966). MC-13
[ReI₄(py)₂]
Tetraiodobis(pyridine) rhenium (IV) Reported by R. Colton, R. Levitus and G. Wilkinson, J. Chem.Soc., 4121 (1960). MC-14
Na₃[Fe(CN)₅L] MC-14a L = (py)
Sodium pentacyano(pyridine) ferrate (II) MC-14b L = pyrazine = (pyz)
Sodium pentacyano(pyrazine) ferrate (II) MC-14c L = 4,4'-bipyridine
Sodium pentacyano(4,4'-bipyridine) ferrate (II) MC-14d L = 3,3'-dimethyl-4,4'-bipyridine
Sodium pentacyano(3,3'-dimethyl-4,4'-bipyridine) ferrate (II) MC-14e L = 3,8-phenanthroline
Sodium pentacyano(3,8-phenanthroline) ferrate (II) MC-14f L = 2,7-diazapyrene
Sodium pentacyano(2,7-diazapyrene) ferrate (II) MC-14g L = 1,4-bis(4-pyridyl)butadiyne
Sodium pentacyano[1,4-bis(4-pyridyl)butadiyne] ferrate (II) a-g Reported by G-H. Lee, L. D. Ciana, A. Haim, J.Am. Chem. Soc., 111, 1235-41 (1989). MC-14h L = (4-py)pyridinium
Sodium pentacyano(4-pyridylpyridinium) ferrate (II) MC-14i L = 1-methyl-4-(4-py)pyridinium
Sodium pentacyano[1-methyl-4-(4-pyridyl)pyridium] ferrate (II) MC-14j L = N-Me-pyrazinium
Sodium pentacyano(N-methyl pyrazinium) ferrate (II) MC-14k
L = 4-Cl(py) Sodium pentacyano (4-chloro pyridino) ferrate (II) h-k Reported by H. E. Toma and J. M. Malin, Inorg. Chem. 12, 1039 (1973). MC-14l L = Ph₃P
Ph = phenyl
Sodium pentacyano(tri phenylphosphine) ferrate (II) Reported by M. M. Monzyk and R. A. Holwerda, Polyhedron, 9, 2433 (1990). MC-14m L = thiourea
Sodium pentacyano (thiourea) ferrate (II) MC-14n L = pyrazole
Sodium pentacyano (pyrazole) ferrate (II) MC-14o L = imidazole
Sodium pentacyano (imidazole) ferrate (II) m-o Reported by C. R. Johnson, W. W. Henderson and R. E. Shepherd, Inorg. Chem., 23, 2754 (1984). MC-14p L = MeNH₂
Sodium pentacyano (methylamine) ferrate (II) MC-14q L = Me₂NH
Sodium pentacyano (dimethylamine) ferrate (II) MC-14r L = Me₃NH
Sodium pentacyano (trimethylamine) ferrate (II) MC-14s L = EtNH₂
Sodium pentacyano (ethylamine) ferrate (II) MC-14t L = BuNH₂
Sodium pentacyano (butylamine) ferrate (II) MC-14u L = cyclohexylamine
Sodium pentacyano (cyclohexylamine) ferrate (II) MC-14v L = piperidine
Sodium pentacyano (piperidine) ferrate (II) MC-14w L = aniline
Sodium pentacyano (aniline) ferrate (II) MC-14x L = morpholine
Sodium pentacyano (morpholine) ferrate (II) MC-14y L = ethanolamine
Sodium pentacyano (ethanolamine) ferrate (II) p-y Reported by N. E. Klatz, P. J. Aymoneno, M. A. Blesa and J. A. Olabe, Inorg. Chem. 17, 556 (1978). MC-14z L = P(OBu)₃
Sodium pentacyano(tributyl phosphite) ferrate (II) MC-14aa L = P(Bu)₃
Sodium pentacyano[(tri butyl)phosphine] ferrate (II) z-aa Reported by V. H. Inouye, E. Fluck, H. Binder and S. Yanagisawa, Z. Anorg. Allgem. Chem., 483, 75-85 (1981). MC-14bb L = p-nitroso-N,N-dimethylaniline
Sodium pentacyano(p-nitroso-N,N-dimethylaniline) ferrate (II) MC-14cc L = nitrosobenzene
Sodium pentacyano(nitroso benzene) ferrate (II) MC-14dd L = 4-CN-(py)
Sodium pentacyano(4-cyano pyridine) ferrate (II) bb-dd Reported by Z. Bradic, M. Pribanic and S. Asperger, J. Chem. Soc., 353 (1975). MC-14ee L = 3-[(H₅C₂)₂NC(O)] (py)
Sodium pentacyano-(nicotinamide) ferrate (II) MC-14ff L = 4-[NH₂NHC(O)] (py)
Sodium pentacyano(iso nicotinoylhydrazine) ferrate (II) MC-14gg L = 3-CHO-(py)
Sodium pentacyano (nicotinaldehyde) ferrate (II) MC-14hh L = 3-[NH₂C(O)] (py)
Sodium pentacyano (nicotinamide) ferrate (II) MC-14ii L = 4-[NH₂C(O)] (py)
Sodium pentacyano(iso nicotinamide) ferrate (II) MC-14jj L = 3-[^-OC(O)] (py)
Sodium pentacyano (nicotinato) ferrate (II) MC-14kk L = 4-[^-OC(O)] (py)
Sodium pentacyano(iso nicotinato) ferrate (II) MC-14ll L = 3-[^-OC(O)CH₂NHC(O)] (py)
Sodium pentacyano(nico tinoylglycinato) ferrate (II) MC-14mm L = [H₂NC(O)] (pyz)
Sodium pentacyano(pyrazine amide) ferrate (II) MC-14nn L = (pyz)-mono-N-oxide
Sodium pentacyano(pyrazine mono-N-oxide) ferrate (II) ee-nn Reported by P. J. Morando, U. I. E. Bruyere and M. A. Blesa, Transition Metal Chem., 8, 99 (1983). MC-14oo L = 4-Ph(py)
Sodium pentacyano(4-phenyl pyridine) ferrate (II) MC-14pp L = pyridazine
Sodium pentacyano (pyridazine) ferrate (II) MC-14qq L = pyrimidine
Sodium pentacyano (pyrimidine) ferrate (II) oo-qq Reported by D. K. Lavallee and E. B. Fleischer, J. Am. Chem. Soc., 94 (8), 2583 (1972). MC-14rr L = Me₂SO
Sodium pentacyano(dimethyl sulfoxide) ferrate (II) Reported by H. E. Toma, J. M. Malin and E. Biesbrecht, Inorg. Chem., 12, 2884 (1973). MC-15 K₃[Ru(CN)₅L] MC-15a L = (pyz)
Potassium pentacyano (pyrazine) ruthenate (II) Reported by C. R. Johnson and R. E. Shepherd, Inorg. Chem., 22, 2439 (1983). MC-15b L = methylpyrazinium
Potassium pentacyano (methylpyrazinium) ruthenate (II) MC-15c L = imidazole
Potassium pentacyano (imidazole) ruthenate (II) MC-15d L = 4-pyridylpyridinium
Potassium pentacyano (4-pyridylpyridinium) ruthenate (II) MC-15e L = 4,4'-bipyridine
Potassium pentacyano (4,4'-bipyridine) ruthenate (II) MC-15f L = Me₂SO
Potassium pentacyano (dimethylsulfoxide) ruthenate (II) MC-15g L = (py)
Potassium pentacyano (pyridine) ruthenate (II) MC-15h L = 4-[^-OC(O)](py)
Potassium pentacyano (isonicotinato) ruthenate (II) b-h Reported by M. A. Hoddenbagh and D. A. McCartney, Inorg. Chem., 25., 2099 (1986). MC-16
K₂[CO(CN)₅L] MC-16a L = Me
Potassium pentacyano (methyl) cobaltate (III) MC-16b L = Et
Potassium pentacyano(ethyl) cobaltate (III) MC-16c L = tolyl
Potassium pentacyano(tolyl) cobaltate (III) MC-16d L = acetamide
Potassium pentacyano(acetamide) cobaltate (III) MC-16e L = -CH₂C(O)O^-
Potassium pentacyano(acetato) cobaltate (III) MC-16f L = -CH₂C(O)OCH₃
Potassium pentacyano(methyl acetato) cobaltate (III) MC-16g L = -CH₂CH₂C(O)OCH₃Me
Potassium pentacyano(methyl proponato) cobaltate (III) a-g Reported by J. Halpern and J. P. Maher, J. Am. Chem. Soc., 87, 5361 (1965). MC-17
K[Co(CN)₄(en)]
Potassium tetracyano (ethylenediamine) cobaltate (III) Reported by K. Ohkawa, J. Fujita and Y. Shimura, Bulletin of the Chemical Society of Japan, 42, 3184-9 (1969). MC-18
Ba[Co(CN)₄(tn)]
(tn) = trimethylenediamine Barium tetracyano(trimethylenediamine) cobaltate (III) Reported by K. Ohkawa, J. Fujita and Y. Shimura, Bulletin of the Chemical Society of Japan, 42, 3184-9 (1969). MC-19
[RhL₃Cl₃] MC-19a L = MeCN
Tris (acetonitrile) trichloro rhodium (III) MC-19b L = PhCN
Tris(benzonitrile) trichloro rhodium (III) a-b Reported by G. Beech and G. Marr, J. Chem. Soc. (A), 2904 (1970). MC-20
Na₂[RhCl₅(SMe₂)]
Sodium pentachloro(di methylsulfide) rhodate (III) Reported by S. J. Anderson, J. R. Barnes, P. L. Goggin and R. S. Goodfellow, J. Chem. Res. (M), 3601 (1978). MC-21
cis, trans-[RhX₄(SMe₂)₂]
X = halo
cis or trans-Tetrahalobis (dimethylsulfide) rhodate (III) Reported by S. J. Anderson, J. R. Barnes, P. L. Goggin and R. S. Goodfellow, J.Chem.Res.(M), 3601 (1978). MC-22
mer,fac-[RhX₃(SMe₂)₃]
met or fac-Trihalotris (di methylsulfide) rhodate (III) Reported by S. J. Anderson, J. R. Barnes, P. L. Goggin and R. S. Goodfellow, J. Chem. Res. (M), 3601 (1978). MC-23
cis,trans-[N(C₃H₇)₄] [RhCl₄ (Me₂SO)₂]
Tetrapropylammonium tetrachloro bis(dimethylsulfoxide) rhodium (III) Reported by Y. N. Kukushkin, N. D. Rubtsora and N. Y. Irannikova, Russ. J.Inorg. Chem. (Trans. Ed.), 15, 1032 (1970). MC-24
[RhCl₃(Me₂SO)₃]
Trichlorotris(di methylsulfoxide) rhodium (III) Reported by Y. N. Kukushkin, N. D. Rubtsora and N. Y. Irannikova, Russ.J.Inorg. Chem. (Trans. Ed.), 15, 1032 (1970). MC-25
K[RhCl₄L] MC-25a L = 1,10-phenanthroline
Potassium tetrachloro(1,10-phenanthroline) rhodate (III) MC-25b L = 5-methyl(1,10-phenanthroline)
Potassium tetrachloro[5-methyl(1,10-phenanthroline)] rhodate (III) MC-25c L = 5,6-dimethyl(1,10-phenanthroline)
Potassium tetrachloro[5,6-dimethy-(1,10-phenanthroline)] rhodate (III) MC-25d L = 5-bromo(1,10-phenanthroline)
Potassium tetrachloro[5-bromo(1,10-phenanthroline)] rhodate (III) MC-25e L = 5-chloro(1,10-phenanthroline)
Potassium tetrachloro[5-chloro(1,10-phenanthroline)] rhodate (III) MC-25f L = 5-nitro(1,10-phenanthroline)
Potassium tetrachloro[5-nitro(1,10-phenanthroline)] rhodate (III) MC-25g L = 4,7-diphenyl(1,10-phenanthroline
Potassium tetrachloro(1,10-phenanthroline) rhodate (III) a-g Reported by R. J. Watts and J. Van Houten, J.Am. Chem. Soc., 96, 4334 (1974). MC-26
K[IrX₄(en)] MC-26a X = Cl
Potassium tetrachloro(ethyl enediamine) iridate (III) MC-26b X = Br
Potassium tetrabromo(ethyl enediamine) iridate (III) a-b Reported by I. B. Barnovskii, R. E. Sevast'ynova, G. Y. Mazo and V. I. Nefadov, Russ. J. of Inorg. Chem., (Trans. Ed.) 19, 1974. MC-27
K[IrCl_x(MeCN)_y] MC-27a x = 4, y = 2
Potassium tetrachloro bis(acetonitrile) iridate (III) MC-27b x = 5, y = 1
Potassium pentachloro (acetonitrile) iridate (III) a-b Reported by B. D. Catsikis and M. L. Good, Inorg. Nucl. Chem. Lett., 9, 1129-30 (1973). MC-28
[N(Me)₄] [IrCl₄(MeSCH₂CH₂SMe)]
Tetramethylammonium tetrachloro-(2,5-dithiahexane) iridate (III) Reported by D. J. Gulliver, W. Levason, K. G. Smith and M. J. Selwood, J. Chem. Soc. Dalton trans, 1872-8 (1980). MC-29
K_m[IrX_x (pyz)_yL_n] MC-29a X = Cl, m = 2, n = 0, x = 5, y = 1
Potassium pentachloro (pyrazine) iridate (III) MC-29b X = Cl, m = 1, n = 0, x = 4, y = 2, cis isomer
Potassium tetrachloro biscis (pyrazine) iridate (III) MC-29c X = Cl, m = 1, n = 0, x = 4, y = 2, trans isomer
Potassium tetrachloro bistrans (pyrazine) iridate (III) MC-29d X = Cl, m = 1, n= 0, x = 3, y = 3
Potassium trichloro tris(pyrazine) iridate (III) a-d Reported by F. Lareze, C. R. Acad. Sc. Paris, 261, 3420 (1965). MC-30 K₂[IrCl₅ (pyrimidine)]
Potassium pentachloro (pyrimidine) iridate (III) Reported by F. Larese and L. Bokobza-Sebagh, C.R.Acad. Sc.Paris, 277, 459 (1973). MC-31 K₄[Ir₂Cl₁₀(pyz)]
Potassium decachloro (µ-pyrazine) bis [pentachloroiridate (III)] Reported by F. Lareze, C. R. Acad. Sc. Paris, 282, 737 (1976). MC-32
K_m[IrCl_x(py)_yL_n] MC-32a m = 2, n = 0, x = 5, y = 1
Potassium pentachloro (pyridine) iridate (III) MC-32b m = 1, n = 0, x = 4, y = 2
Potassium tetrachloro bis(pyridine) iridate (III) MC-32c m = 0, n = 0, x = 3, y = 3
Trichlorotris(pyridine) iridate (III) MC-32d L = pyridazine, m = 0, n = 1, x = 5, y = 0
Potassium pentachloro (pyridazine) iridate (III) a-d Reported by G. Rio and F. Larezo, Bull. Soc. Chim. France, 2393 (1975). MC-32e L = (C₂O₄), m = 2, n = 1, x = 3, y = 1
Potassium trichloro(oxalate) (pyridine) iridate (III) Reported by Y. Inamura, Bull. Soc. China, 7, 750 (1940). MC-32f L = (HOH), m = 0, n = 1, x = 3, y = 2
Trichloromonoaquo (pyridine iridium (III) Reported by M. Delepine, Comptes Rendus, 200 , 1373 (1935). MC-33
K₃[IrCl₄(C₂O₄)]
Potassium tetrachloro oxalato iridate (III) Reported by A. Duffour, Comptes Rendus, 152 , 1393 (1911). MC-34
[In(thiourea)₃(NCS)₃]
Tris(isothiocyanato) trithiourea indium (III) Reported by S. J. Patel, D. B. Sowerby and D. G. Tuck, J.Chem.Soc.(A), 1188 (1967). MC-35
[In(dimac)₃(NCS)₃]
dimac = N,N-dimethylacetamide Tris(N,N-dimethylacetamide) tris(isothiocyanato) indium (III) Reported by S. J. Patel, D. B. Sowerby and D. G. Tuck, J. Chem. Soc.(A), 1188 (1967). MC-36
[Et₄N]₂[Me_mSn(SCN)_n] MC-36a m = 2, n = 4
Tetraethylammonium dimethyl tetra(isothiocyanato) stannate MC-36b m = 1, n = 5
Tetraethylammonium methyl penta(isothiocyanato) stannate a-b Reported by A. Cassal, R. Portanova and Barbieri, J. Inorg. Nucl. Chem., 27, 2275 (1965). MC-37
Na₆[Fe₂(CN)₁₀(pyz)]
Sodium decacyano (µ-pyrazine) diferrate (II) Reported by J. M. Malin, C. F. Schmitt, H. E. Toma, Inorg. Chem., 14, 2924 (1975) MC-38
Na₆[Fe₂(CN)₁₀ (µ-4, 4'-bipyridine) ]
Sodium decacyano (µ-4,4'-bipyridine) diferrate (II) Reported by J. E. Figard, J. V. Paukstelis, E. F. Byrne and J. D. Peterson, J. Am. Chem. Soc., 99, 8417 (1977). MC-39
Na₆[Fe₂(CN)₁₀L]
L = trans-1, 2-bis (4-pyridyl) ethylene
Sodium decacyano[µ-trans-1,2-bis (4-pyridyl) ethylene] diferrate (II) Reported by N. E. Katz, An. Quim. Ser. B, 77(2), 154-6. MC-40 Na₅ [(CN)₅FeLCo(CN)₅] MC-40a L = (pyz)
Sodium decacyano (µ-pyrazine) ferrate (II) cobaltate (III) MC-40b L = 4,4'-bipyridine
Sodium decacyano (µ-4, 4'-bipyridine) ferrate (II) cobaltate (III) MC-40c L = 4-cyanopyridine
Sodium decacyano (µ-4-cyanopyridine) ferrate (II) cobaltate (III) Reported by K. J. Pfenning, L. Lee, H. D. Wohlers and J. D. Peterson, Inorg. Chem., 21, 2477 (1982).
In addition to the illustrative known compounds, compounds not located in the literature have been synthesized and employed in the practice of the invention. These compounds include the following: MC-41
K₂[IrCl₅(thiazole)]
Potassium pentachloro (thiazole) iridate (III) MC-42
Na₃K₂[IrCl₅(pyz)Fe(CN)₅]
Potassium sodium pentachloro iridate (III) (µ-pyrazine) pentacyanoferrate (II) MC-43
K₅[IrCl₅(pyz)Ru(CN)₅]
Potassium pentachloro iridate (III) (µ-pyrazine) pentacyano ruthenate (II) MC-44
Na₃K₃[Fe(CN)₅(pyz)Ru(CN)₅]
Potassium sodium decacyano (µ-pyrazine) ferrate (II) ruthenate (II) MC-45
K₂[Rh(CN)₅(tz)]
tz = thiazole
Potassium pentacyano (thiazole) rhodate (III) MC-46
Na₄[Rh₂Cl₁₀(pyz)]
Sodium decachloro (pyrazine) rhodate (III) MC-47
Rh[Cl₃(oxazole)₃]
Trichloro tris(oxazole) rhodium (III) MC-48
Na₃[Fe(CN)₅TQ]
TQ = (5-triazolo[4,3-a]quinoline)
Sodium pentacyano(5-triazolo-[4,3-a]quinoline) ferrate (II) MC-49
K[IrCl₄(tz)₂]
Potassium tetrachloro (thiazole) iridate (III) MC-50
K₂[IrBr₅(tz)]
Potassium pentabromo (thiazole) iridate (III) MC-51
K[IrBr₄(tz)₂]
Potassium tetrabromo bis(thiazole) iridate (III) MC-52
K[IrCl₄(H₂O) (tz)]
Potassium aquo tetrachloro (thiazole) iridate (III) MC-53
K[IrCl₄ (4-methylthiazole) ₂]
Potassium bis(4-methylthiazole) tetrachloro iridate (III) MC-54
K₂[IrCl₅(5-methylthiazole)]
Potassium (5-methylthiazole) pentachloro iridate (III) MC-55
K[IrCl₄(5-methylthiazole)₂]
Potassium bis(5-methylthiazole) tetrachloro iridate (III) MC-56
K[IrCl₄(4,5-dimethylthiazole)₂]
Potassium bis(4,5-dimethylthiazole) tetrachloro iridate (III) MC-57
K[IrCl₄(2-bromothiazole)₂]
Potassium bis(2-bromothiazole) tetrachloro iridate (III) MC-58
K[IrCl₄(2-methyl-2-thiazoline)₂]
Potassium bis(2-methyl-2-thiazoline) tetrachloro iridate (III) MC-59
K₂[IrCl₅(3-chloropyrazine)]
Potassium (3-chloropyrazine) pentachloro iridate (III) MC-60
K₂[IrCl₅(3,5-dichloropyrazine)]
Potassium (3,5-dichloropyrazine) pentachloro iridate (III) MC-61
K₂[IrCl₅(3-methylpyrazine)]
Potassium (3-methylpyrazine) pentachloro iridate (III) MC-62
K₂[IrCl₅(3,5-dimethylpyrazine)]
Potassium (3,5-dimethylpyrazine) pentachloro iridate (III) MC-63
K₂[IrCl₅(3-methoxypyrazine)]
Potassium (3-methoxypyrazine) pentachloro iridate (III) MC-64
K₂ [IrCl₅(3-cyanopyrazine)]
Potassium pentachloro (3-cyanopyrazine) iridate (III) MC-65
K₂ [IrCl₅(2,5-dimethylpyrazine)]·1/3CH₃OH
Potassium (2,5-dimethylpyrazine) pentachloro iridate (III) methanol MC-66
[N-CH₃N₂C₄H₄] [IrCl₅(4-CH₃N₂C₄H₄)]
N-Methylpyrazinium (N-methylpyrazinium) pentachloro iridate (III) Preparations of these compounds are presented below.
Generally any C-C, H-C or C-N-H organic ligand capable of forming a dopant metal hexacoordination complex with at least half of the metal coordination sites occupied by halide or pseudohalide ligands can be employed. This, of course, excludes coordination complexes such as metal ethylenediaminetetraacetic acid (EDTA) complexes, since EDTA itself occupies six coordination sites and leaves no room for other ligands. Similarly, tris(oxalate) and bis(oxalate) metal coordination complexes occupy too many metal coordination sites to allow the required inclusion of other ligands.
By definition, to be considered C-C, H-C or C-N-H organic a ligand must include at least one carbon-to-carbon bond, at least one carbon-to-hydrogen bond or at least one hydrogen-to-nitrogen-to-carbon bond linkage. A simple example of an organic ligand classifiable as such solely by reason of containing a carbon-to-carbon bond is an oxalate (-O(O)C-C(O)O-) ligand. A simple example of an organic ligand classifiable as such solely by reason of containing a carbon-to-hydrogen bond is a methyl (-CH₃) ligand. A simple example of a C-C, H-C or C-N-H organic ligand classifiable as such solely by reason of containing a hydrogen-to-nitrogen-to-carbon bond linkage is a ureido [-HN-C(O)-NH-] ligand. All of these ligands fall within the customary contemplation of C-C, H-C or C-N-H organic ligands. The organic ligand definition excludes compounds lacking C-C, H-C or C-N-H organic characteristics, such as ammonia, which contains only nitrogen-to-hydrogen bonds, and carbon dioxide, which contains only carbon-to-oxygen bonds.
The realization of useful photographic performance modifications through the use of C-C, H-C or C-N-H organic ligands is based on performance comparisons and is independent of any particular theory. By comparing the C-C, H-C or C-N-H organic ligand definition bonding requirements with the bonds present in ligands heretofore reported to have been incorporated in silver halide grain structures, it is recognized that the definitionally required bonding present in the organic ligands differentiates them structurally from known ligand dopants. The balancing of halide and pseudohalide ligands with one or more C-C, H-C or C-N-H organic ligands to achieve useful photographic effects is consistent with the halide and pseudohalide ligands occupying halide ion lattice sites in the crystal structure. On the other hand, the diversity of size and steric forms of the C-C, H-C or C-N-H organic ligands shown to be useful supports the position that photographic effectiveness extends beyond the precepts of prior substitutional models. It is now specifically contemplated that C-C, H-C or C-N-H organic ligand effectiveness can be independent of size or steric configuration and is limited only by their availability in metal dopant ion hexacoordination complexes. Nevertheless, since there is no known disadvantage for choosing C-C, H-C or C-N-H organic ligands based on host crystal lattice steric compatibility or approximations of steric compatibility nor have any advantages been identified for increasing ligand size for its own sake, the preferred C-C, H-C or C-N-H organic ligand selections discussed below are those deemed most likely to approximate host crystal lattice compatibility. In other words, while the precept of host crystal lattice matching as an essential prerequisite of ligand utility has been discredited, there are significant advantages to be gained by selecting C-C, H-C or C-N-H organic ligands on the basis of their exact or approximate conformation to the host crystal lattice.
In general preferred individual C-C, H-C or C-N-H organic ligands contain up to 24 (optimally up to 18) atoms of sufficient size to occupy silver or halide ion sites within the grain structure. Stated another way, the C-C, H-C or C-N-H organic ligands preferably contain up to 24 (optimally up to 18) nonmetallic atoms. Since hydrogen atoms are sufficiently small to be accommodated interstitially within a silver halide face centered cubic crystal structure, the hydrogen content of the organic ligands poses no selection restriction. While organic ligands can contain metallic ions, these also are readily sterically accommodated within the crystal lattice structure of silver halide, since metal ions are, in general, much smaller than nonmetallic ions of similar atomic number. For example, silver ion (atomic number 47) is much smaller than bromide ion (atomic number 35). In the overwhelming majority of instances the organic ligands consist of hydrogen and nonmetallic atoms selected from among carbon, nitrogen, oxygen, fluorine, sulfur, selenium, chlorine and bromine. The steric accommodation of iodide ions within silver bromide face centered cubic crystal lattice structures is well known in photography. Thus, even the heaviest non-metallic atoms, iodine and tellurium, can be included within the C-C, H-C or C-N-H organic ligands, although their occurrence is preferably limited (e.g., up to 2 and optimally only 1) in any single organic ligand.
Referring to the illustrations of C-C, H-C or C-N-H organic ligand containing coordination complexes above, it is apparent that a wide variety of C-C, H-C or C-N-H organic ligands are available for selection. Organic ligands can be selected from among a wide range of organic families, including substituted and unsubstituted aliphatic and aromatic hydrocarbons, secondary and tertiary amines (including diamines and hydrazines), phosphines, amides (including hydrazides), imides, nitriles, aldehydes, ketones, organic acids (including free acids, salts and esters), sulfoxides, and aliphatic and aromatic heterocycles including chalcogen (i.e., oxygen, sulfur, selenium and tellurium) and pnictide (particularly nitrogen) hetero ring atoms. The following are offered as nonlimiting illustrations of preferred organic ligand categories:
Aliphatic hydrocarbon ligands containing up to 10 (most preferably up to 6) nonmetallic (e.g., carbon) atoms, including linear, branched chain and cyclic alkyl, alkenyl, dialkenyl, alkynyl and dialkynyl ligands.
Aromatic hydrocarbon ligands containing 6 to 14 ring atoms (particularly phenyl and naphthyl).
Aliphatic azahydrocarbon ligands containing up to 14 nonmetallic (e.g., carbon and nitrogen) atoms. The term "azahydrocarbon" is employed to indicate nitrogen atom substitution for at least one, but not all, of the carbon atoms. The most stable and hence preferred azahydrocarbons contain no more than one nitrogen-to-nitrogen bond. Both cyclic and acyclic azahydrocarbons are particularly contemplated.
Aliphatic and aromatic nitriles containing up to 14 carbon atoms, preferably up to 6 carbon atoms.
Aliphatic ether and thioether ligands, the latter also being commonly named as thiahydrocarbons in a manner analogous to azahydrocarbon ligands. Both cyclic and acyclic ethers and thioethers are contemplated.
Amines, including diamines, most preferably those containing up to 12 (optimally up to 6) nonmetal (e.g., carbon) atoms per nitrogen atom organic substituent. Note that the amines must be secondary or tertiary amines when in the form of a ligand, since a primary amine (H₂N-), designated by the term "amine" used alone, does not satisfy the organic ligand definition.
Amides, most preferably including up to 12 (optimally up to 6) nonmetal (e.g., carbon) atoms.
Aldehydes, ketones, carboxylates, sulfonates and phosphonates (including mono and dibasic acids, their salts and esters) containing up to 12 (optimally up to 7) nonmetal (e.g., carbon) atoms.
Aliphatic sulfoxides containing up to 12 (preferably up to 6) nonmetal (e.g., carbon) atoms per aliphatic moiety.
Aromatic and aliphatic heterocyclic ligands containing up to 18 ring atoms with heteroatoms typically being selected from among pnictides (e.g., nitrogen) and chalcogens (e.g., oxygen, sulfur, selenium and tellurium). The heterocyclic ligands contain at least one five or six membered heterocyclic ring, with the remainder of the ligand being formed by ring substituents, including one or more optional pendant or fused carbocyclic or heterocyclic rings. In their simplest form the heterocycles contain only 5 or 6 non-metallic atoms. Exemplary nonlimiting illustrations of heterocyclic ring structures include furans, thiophenes, azoles, diazoles, triazoles, tetrazoles, oxazoles, thiazoles, imidazoles, azines, diazines, triazines, as well as their dihydro (e.g., oxazoline, thiazoline and imidazoline), bis (e.g., bipyridine) and fused ring counterparts (e.g, benzo- and naptho- analogues). When a nitrogen hetero atom is present, each of trivalent, protonated and quaternized forms are contemplated. Among specifically preferred heterocyclic ring moieties are those containing from 1 to 3 ring nitrogen atoms and azoles containing a chalcogen atom.
All of the above C-C, H-C or C-N-H organic ligands can be either substituted or unsubstituted. Any of a broad range of stable and synthetically convenient substituents are contemplated. Halide, pseudohalide, hydroxyl, nitro and organic substituents that are linked directly or through divalent oxygen, sulfur or nitrogen linkages are specifically contemplated, where the organic substituents can be simple or composite forms of the types of organic substituents named above.
The requirement that at least one of the coordination complex ligands be a C-C, H-C or C-N-H organic ligand and that half of the ligands be halide or pseudohalide ligands permits one or two of the ligands in hexacoordination complexes to be chosen from among ligands other than C-C, H-C or C-N-H organic, halide and pseudohalide ligands. For example, nitrosyl (NO), thionitrosyl (NS), carbonyl (CO), oxo (O) and aquo (HOH) ligands are all known to form coordination complexes that have been successfully incorporated in silver halide grain structures. These ligands are specifically contemplated for inclusion in the coordination complexes satisfying the requirements of the invention.
In general any known dopant metal ion coordination complex containing the required balance of halo and/or pseudohalo ligands with one or more C-C, H-C or C-N-H organic ligands can be employed in the practice of the invention. This, of course, assumes that the coordination complex is structurally stable and exhibits at least very slight water solubility under silver halide precipitation conditions. Since silver halide precipitation is commonly practiced at temperatures ranging down to just above ambient (e.g., typically down to about 30°C), thermal stability requirements are minimal. In view of the extremely low levels of dopants that have been shown to be useful in the art, only extremely low levels of water solubility are required.
The C-C, H-C or C-N-H organic ligand containing coordination complexes satisfying the requirements above can be present during silver halide emulsion precipitation in any conventional level known to be useful for the metal dopant ion. Evans U.S. Patent 5,024,931, discloses effective doping with coordination complexes containing two or more Group VIII noble metals at concentrations that provide on average two metal dopant ions per grain. To achieve this, metal ion concentrations of 10^-10 M are provided in solution, before blending with the emulsion to be doped. Typically useful metal dopant ion concentrations, based on silver, range from 10^-10 to 10^-3 gram atom per mole of silver. A specific concentration selection is dependent upon the specific photographic effect sought. For example, Dostes et al Defensive Publication T962,004 teaches metal ion dopant concentrations ranging from as low as 10^-10 gram atom/Ag mole for reducing low intensity reciprocity failure and kink desensitization in negative-working emulsions; Spence et al U.S. Patents 3,687,676 and 3,690,891 teach metal ion dopant concentrations ranging as high as 10^-3 gram atom/Ag mole for avoidance of dye desensitization. While useful metal ion dopant concentrations can vary widely, depending upon the halide content of the grains, the metal ion dopant selected, its oxidation state, the specific ligands chosen, and the photographic effect sought, concentrations of less than 10^-6 gram atom/Ag mole are contemplated for improving the performance of surface latent image forming emulsions without significant surface desensitization. Concentrations of from 10^-9 to 10^-6 gram atom/Ag mole have been widely suggested. Graphic arts emulsions seeking to employ metal dopants to increase contrast with incidental or even intentionally sought speed loss often range somewhat higher in metal dopant concentrations than other negative-working emulsions, with concentrations of up to 10^-4 gram atom/Ag mole being common. For internal electron trapping, as is commonly sought in direct-positive emulsions, concentrations of greater than 10^-6 gram atom/Ag mole are generally taught, with concentrations in the range of from 10^-6 to 10^-4 gram atom/Ag mole being commonly employed. For complexes that contain a single metal dopant ion molar and gram atom concentrations are identical; for complexes containing two metal dopant ions gram atom concentrations are twice molar concentrations; etc. Following the accepted practice of the art, stated dopant concentrations are nominal concentrations--that is, they are based on the dopant and silver added to the reaction vessel prior to and during emulsion precipitation.
The metal dopant ion coordination complexes can be introduced during emulsion precipitation employing procedures well known in the art. The coordination complexes can be introduced during precipitation of the host grain portions as well as during precipitation of the epitaxially deposited host grain portions. It is preferred, however, that the metal dopant coordination complexes containing one or more C-C, H-C or C-N-H organic ligands be introduced primarily and, most preferably, entirely during precipitation of the epitaxially deposited surface portions of the grains. Typically the coordination complexes are introduced at least in part during precipitation through one of the halide ion or silver ion jets or through a separate jet. Typical types of coordination complex introductions are disclosed by Janusonis et al, McDugle et al, Keevert et al, Marchetti et al and Evans et al, each cited above. Another technique, demonstrated in the Examples below, for coordination complex incorporation is to precipitate Lippmann emulsion grains in the presence of the coordination complex followed by ripening the doped Lippmann emulsion grains onto host grains.
The emulsions prepared can, apart from the features described above, take any convenient conventional form. Conventional emulsion compositions and methods for their preparation are summarized in Research Disclosure, Item 36544, Section I, cited above, as well as in Vol. 308, December 1989, Item 308119, Section I. Other conventional photographic features are disclosed in the following sections of Item 308119:
II. Emulsion washing;
III. Chemical sensitization;
IV. Spectral sensitization and desensitization;
V. Brighteners;
VI. Antifoggants and stabilizers;
VII. Color materials;
VIII. Absorbing and scattering materials;
IX. Vehicles and vehicle extenders;
X. Hardeners;
XI. Coating aids;
XII. Plasticizers and lubricants;
XIII. Antistatic layers;
XIV. Methods of addition;
XV. Coating and drying procedures;
XVI. Matting agents;
XVII. Supports;
XVIII. Exposure;
XIX. Processing;
XX. Developing agents;
XXI. Development modifiers;
XXII. Physical development systems;
XXIII. Image-transfer systems;
XXIV. Dry development systems;

II. Vehicles, vehicle extenders, vehicle-like addenda and vehicle related addenda;
III. Emulsion washing;
IV. Chemical sensitization;
V. Spectral sensitization and desensitization
VII. Antifoggants and stabilizers;
VII. Color materials;
VIII. Absorbing and scattering materials;
IX. Coating physical property modifying materials;
X. Dye image formers and modifiers;
XI. Layers and layer arrangements;
XII. Features applicable only to color negative;
XIII. Features applicable only to color positive;
XIV. Scan facilitating features;
XV. Supports;
XVI. Exposure;
XVII. Physical development systems;
XVIII. Chemical development systems;
XIX. Development;
XX. Desilvering, washing, rinsing and stabilizing.

Although the invention has general applicability to the modification of photographic emulsions known to employ metal dopant ions for modification of photographic performance, specific applications have been observed that are particularly advantageous.
Rhodium hexahalides represent one well known and widely employed class of dopants employed to increase photographic contrast. Generally the dopants have been employed in concentration ranges of 10^-6 to 10^-4 gram atom of rhodium per mole of silver. Rhodium dopants have been employed in all silver halides exhibiting a face centered cubic crystal lattice structure. However, a particularly useful application for rhodium dopants is in graphic arts emulsions. Graphic arts emulsions typically contain at least 50 mole percent chloride based on silver and preferably contain more than 90 mole percent chloride.
One difficulty that has been encountered using rhodium hexahalide dopants is that they exhibit limited stability, requiring care in selecting the conditions under which they are employed. It has been discovered that the substitution of an C-C, H-C or C-N-H organic ligand for one or two of the halide ligands in rhodium hexahalide results in a more stable hexacoordination complex. Thus, it is specifically contemplated to substitute rhodium complexes of the type disclosed in this patent application for rhodium hexahalide complexes that have heretofore been employed in doping photographic emulsions.
In another specific application, it is recognized that spectral sensitizing dye, when adsorbed to the surface of a silver halide grain, allows the grain to absorb longer wavelength electromagnetic radiation. The longer wavelength photon is absorbed by the dye, which is in turn adsorbed to the grain surface. Energy is thereby transferred to the grain allowing it to form a latent image.
While spectral sensitizing dyes provide the silver halide grain with sensitivity to longer wavelength regions, it is quite commonly stated that the dyes also act as desensitizers. By comparing the native sensitivity of the silver halide grains with and without adsorbed spectral sensitizing dye it is possible to identify a reduction in native spectral region sensitivity attributable to the presence of adsorbed dye. From this observation as well as other, indirect observations it is commonly accepted that the spectral sensitizing dyes also are producing less than their full theoretical capability for sensitization outside the spectral region of native sensitivity.
It has been observed quite unexpectedly that increased spectral sensitivity of emulsions containing adsorbed spectral sensitizing dyes can be realized when the silver halide grains are doped with a group 8 metal dopant forming a hexacoordination complex containing at least one C-C, H-C or C-N-H organic ligand and pseudohalide ligands containing Hammett sigma values more positive than 0.50. The following pseudohalide meta Hammett sigma values are exemplary: CN 0.61, SCN 0.63 and SeCN 0.67. The meta Hammett sigma values for bromo, chloro and iodo ligands are in the range of from 0.35 to 0.39. The surprising effectiveness of the pseudohalide ligand containing complexes as compared to those that contain halide ligands is attributed to the greater electron withdrawing capacity of the pseudohalide ligands satisfying the stated Hammett sigma values. Further, the sensitizing effect has shown itself to be attainable with spectral sensitizing dyes generally accepted to have desensitizing properties either as the result of hole or electron trapping. On this basis it has been concluded that the dopants are useful in all latent image forming spectrally sensitized emulsions. The dopant can be located either uniformly or non-uniformly within the grains. For maximum effectiveness the dopants are preferably present within 500 Å(50nm) of the grain surface, and are optimally separated from the grain surface by at least 50 Å(5nm). Preferred metal dopant ion concentrations are in the range of from 10^-5 to 10^-8 gram atom/Ag mole.
In another form it is contemplated to employ cobalt coordination complexes satisfying the requirements of the invention to reduce photographic speed with minimal (<5%) or no alteration in photographic contrast. One of the problems that is commonly encountered in preparing photographic emulsions to satisfy specific aim characteristics is that, in adjusting an emulsion that is objectionable solely on the basis of being slightly too high in speed for the specific application, not only speed but the overall shape of the characteristic curve is modified.
In has been discovered quite unexpectedly that cobalt hexacoordination complexes satisfying the general requirements of the invention are capable of translating a characteristic curve along the log E (E = lux-second) exposure axis without significantly altering the shape of the characteristic curve. Specifically, contrast and minimum and maximum densities can all be maintained while decreasing sensitivity by doping. Preferred cobalt complexes are those that contain, in addition to one or two organic ligands occupying up to two coordination sites, pseudohalide ligands that exhibit Hammett sigma values of that are more positive than 0.50. The cobalt complex can be uniformly or non-uniformly distributed within the grains. Cobalt concentrations are preferably in the range of from 10^-6 to 10^-9 gram atom/Ag mole.
In still another specific application of the invention it has been observed that group 8 metal coordination complexes satisfying the requirements of the invention that contain as the C-C, H-C or C-N-H organic ligand an aliphatic sulfoxide are capable of increasing the speed of high (>50 mole %) chloride emulsions and are capable of increasing the contrast of high (>50 mole %) bromide emulsions. Preferred aliphatic sulfoxides include those containing up to 12 (most preferably up to 6) nonmetal (e.g., carbon) atoms per aliphatic moiety. The coordination complex can occupy any convenient location within the grain structure and can be uniformly or non-uniformly distributed. Preferred concentrations of the group 8 metal are in the range of from 10^-6 to 10^-9 gram atom/Ag mole.
In still another specific application of the invention it has been observed that anionic [MX_xY_yL_z] hexacoordination complexes, where M is a group 8 or 9 metal (preferably iron, ruthenium or iridium), X is halide or pseudohalide (preferably Cl, Br or CN), x is 3 to 5, Y is H₂O, y is 0 or 1, L is a C-C, H-C or C-N-H organic ligand, and z is 1 or 2, are surprisingly effective in reducing high intensity reciprocity failure (HIRF), low intensity reciprocity failure (LIRF) and thermal sensitivity variance and in improving latent image keeping (LIK). As herein employed HIRF is a measure of the variance of photographic properties for equal exposures, but with exposure times ranging from 10^-1 to 10^-4 second. LIRF is a measure of the variance of photographic properties for equal exposures, but with exposure times ranging from 10^-1 to 100 seconds. Although these advantages can be generally compatible with face centered cubic lattice grain structures, the most striking improvements have been observed in high (>50 mole %, preferably ≥90 mole %) chloride emulsions. Preferred C-C, H-C or C-N-H organic ligands are aromatic heterocycles of the type previously described. The most effective C-C, H-C or C-N-H organic ligands are azoles and azines, either unsubstituted or containing alkyl, alkoxy or halide substituents, where the alkyl moieties contain from 1 to 8 carbon atoms. Particularly preferred azoles and azines include thiazoles, thiazolines and pyrazines. Further advantages of complexes containing these ligands are demonstrated in the Examples below.
Also found to be unexpectedly useful in producing the same types of photographic advantages noted above in connection with the anionic [MX_xY_yL_z] hexacoordination complexes are anionic [MZ₅L'M'Z'₅] hexacoordination complexes, where M and M' are group 8 or 9 metals (preferably iron, ruthenium or iridium or any combination), Z and Z' are independently selected from among X, Y and L with the proviso that in at least three occurrences of each of Z and Z' they are X and in zero or 1 occurrence of each of Z and Z' they are H₂O, and L' is a C-C, H-C or C-N-H organic bridging ligand, such as a substituted or unsubstituted aliphatic or aromatic diazahydrocarbon. Specifically preferred bridging C-C, H-C or C-N-H organic ligands include H₂N-R-NH₂, where R is a substituted or unsubstituted aliphatic or aromatic hydrocarbon containing from 2 to 12 nonmetal atoms, as well as substituted or unsubstituted heterocycles containing two ring nitrogen atoms, such as pyrazine, 4,4'-bipyridine, 3,8-phenanthroline, 2,7-diazapyrene and 1,4-[bis(4-pyridyl)]butadiyne. The preferred substituents of the heterocyclic ring atoms are alkyl, alkoxy or halide substituents, where the alkyl moieties contain from 1 to 8 carbon atoms.
The anionic [MX_xY_yL_z] or [MZ₅L'M'Z'₅] hexacoordination complex can be located either uniformly or non-uniformly within the grains; however, in the practice of this invention it is contemplated that the iridate complexes will be located either primarily or exclusively in the epitaxially deposited surface portions of the grains. Concentrations preferably range from 10^-9 to 10^-3 gram atom group 8 or 9 metal/Ag mole. When only group 8 metal is present, such as iron and/or ruthenium, preferred concentrations are in the range of from 10^-7 to 10^-3 gram atom/Ag mole. When a group 9 metal, such as iridium is present, preferred concentrations are in the range of from 10^-5 to 10^-9 gram atom/Ag mole.

Preparations

Since the preparation of metal coordination complexes can be undertaken by the procedures described in the articles in which they are reported, cited above, preparations are provided for only those metal coordination complexes for which no source citation is listed. All of the coordination complexes were characterized using ¹H NMR spectroscopy, infra-red spectroscopy, and uv-visible absorption spectroscopy. Thermogravimetric analysis (TGA) was also used.

Preparation of MC-41

[IrCl₅(thiazole)]^2-: 0.2 g of K₂IrCl₅(H₂O) was reacted with 2 ml thiazole (Aldrich) in 20 ml H₂O and stirred for 3 days. The solution was then evaporated to a small volume and precipitated by adding to 50 ml ethanol. The precipitate was filtered and washed with ethanol. The identity of this compound was confirmed by infrared (IR), ultraviolet and visible (UV/Vis) and nuclear magnetic resonance (NMR) spectroscopies and carbon, hydrogen and nitrogen (CHN) chemical analyses.

Preparation of MC-42

[IrCl₅(pyz)Fe(CN)₅]^5-: Na₃K₂[IrCl₅(pyrazine)Fe(CN)₅] was prepared by reacting equimolar amounts of K₂[IrCl₅(pyrazine)] and Na₃[Fe(CN)₅(NH₃)]·3H₂O in a small amount of H₂O at room temperature for 24 hours. The volume was decreased with flowing nitrogen, and ethyl alcohol added to precipitate the final product. The product was assigned a formula of Na₃K₂[IrCl₅(pyrazine)Fe(CN)₅] by IR, UV/VIS and NMR spectroscopies and by CHN chemical analyses.

Preparation of MC-43

[IrCl₅(pyz)Ru(CN)₅]^5-: The mixed metal dimer K₅[IrCl₅(pyrazine)Ru(CN)₅] was prepared by reacting equimolar amounts of K₃[Ru(CN)₅(pyrazine)] and K₂[IrCl₅(H₂O)] in a small amount of H₂O in a hot water bath at 80 C for 2 hours. The volume was partially reduced with flowing nitrogen, and ethyl alcohol was added to precipitate the final product. The dimer was recrystallized by dissolving in a minimum amount of water and precipitated with ethyl alcohol. The product was assigned as K₅[IrCl₅(pyrazine)Ru(CN)₅] by IR, UV/VIS, and NMR spectroscopies and by CHN chemical analyses.

Preparation of MC-45

[Rh(CN)₅(thiazole)]^2-: The synthesis of this compound was similar to literature methods described by G. L. Geoffroy, M. S. Wrighton, G. S. Hammond and H. B. Gray [Inorg. Chem. 13(2), 430-434, (1974)] with slight changes as described here. 0.5 g of K₃[Rh(CN)₆] was dissolved in 100 ml H₂O and adjusted to a pH of 2 with HClO₄. This solution was irradiated with a mercury lamp in a quartz tube for 24 hours. The solution was then evaporated down to 5 ml and chilled. The KClO₄ was filtered and 1 ml of thiazole in 1 ml of ethanol was added. This solution was again irradiated with the Hg lamp, this time for an hour The volume was reduced, and ethanol was added to produce the final product. The precipitate which was formed was filtered and washed with ethanol. The identity of the compound was confirmed by IR, UV/Vis and NMR spectroscopies.

Preparation of MC-46

[Rh₂Cl₁₀(pyz)]^4-: Na₄[Rh₂Cl₁₀(pyrazine)] was prepared by reacting Na₃RhCl₆·12H₂O with pyrazine in a 2 to 1.05 (5% excess pyrazine) molar ratio at 100 C in a minimum amount of H₂O for 1 hour. Acetone was added to the cooled solution to give an oil and an orange colored liquid with some suspended solid material which was decanted. The oil was washed several times with acetone and decanted. The acetone was removed with a N₂ flow to give a sticky red substance which was then air dried in an oven at 100 C for 1 hour to give a dark red material. This was recrystallized twice by dissolving in a minimum amount of H₂O and precipitated with ethyl alcohol. The final material was filtered, washed with ethyl alcohol, and air dried. The product was assigned as Na₄[Rh₂Cl₁₀(pyrazine)] by IR, UV/Vis and NMR spectroscopies and by CHN chemical analyses.

Preparation of MC-44

[Ru(CN)₅(pyz)Fe(CN)₅]^6-: Na₃K₃[Ru(CN)₅(pyrazine)Fe(CN)₅] was similarly prepared by stirring equimolar amounts of K₃[Ru(CN)₅(pyrazine)] and Na₃[Fe(CN)₅(NH₃)]·3H₂O in a small amount of H₂O at room temperature for 24 hours. The volume was decreased with flowing nitrogen, and ethyl alcohol added to precipitate the final product. The product was assigned as Na₃K₃[Ru(CN)₅(pyrazine)Fe(CN)₅] by IR, UV/VIS and NMR spectroscopies and by CHN chemical analyses.

Preparation of MC-47

[RhCl₃(oxazole)₃]: 0.5 g of (NH₄)₂[RhCl₅(H₂O)] was reacted with 0.5 ml oxazole in 15 ml H₂O for 3 days. The solution was then added to a large amount of acetone whereupon a white precipitate appeared. The precipitate (NH₄Cl) was filtered off. A yellow solid was obtained after evaporating the solvent from the filtrate. This yellow solid was washed with cold acetone in which it was slightly soluble. Slow evaporation of the acetone solution provided bright yellow crystals. The yellow product was assigned as RhCl₃(oxazole)₃ by Infrared, UV/Vis, and NMR spectroscopies and CHN chemical analysis.

Preparation of MC-48

[Fe(CN)₅TQ]^3-: The synthesis of this compound is similar to reported methods of various Na_xFe(CN)₅L compounds [H. E. Toma and J. M. Malin, Inorg. Chem. 12(5), 1039-1045, (1973)]. 0.5 g of Na₃[Fe(CN)₅(NH₃)]·3H₂O was dissolved in 5 ml H₂O and added to 0.26 g of s-triazolo [4,3-a] quinoline in 5 ml ethanol. The solution was mixed for 1 week then evaporated to 2 ml and precipitated by adding to ethanol. This provided an oil and a light brown precipitate. The precipitate was filtered and the solution was decanted from the oil. The oil was dissolved in a small amount of water and added to a large excess of ethanol. This afforded more brown precipitate. The precipitates were washed with ethanol and analyzed using IR, UV/Vis and NMR spectroscopies and CHN chemical analysis.

Preparation of MC-49

[IrCl₄(thiazole)₂]^1-: The bis-thiazole complex was synthesized from K₃IrCl₆ and an excess of thiazole in a homogeneous aqueous solution at ca. 85° C with a reaction time of 2 hours. 5 grams of K₃IrCl₆, 4 grams of thiazole, and 45 ml of H₂O were employed in the reaction. After reducing the volume by 50% with N₂, the aqueous solution was poured into a volume of acetone 4 times the H₂O volume and KIrCl₄(tz)₂ precipitated. Solid KIrCl₄(thiazole)₂ has a pale orange color. The material was filtered and washed with acetone. Due to the high solubility in water, the pale orange bis-substituted material has been assigned as the cis-isomer.

Preparation of MC-50

[IrBr₅(thiazole)]^2-: K₃IrBr₆ was the iridium source for the preparation of the monothiazole complex K₂IrBr₅(thiazole). 2 grams of K₃IrBr₆ and 0.9 grams of thiazole were dissolved in a minimum amount of water and allowed to set at room temperature for 24 hours. During this time the solution assumed a light green color and the addition of an equal volume of acetone precipitated a lustrous green precipitate. This was filtered, washed with 50% water/50% acetone, acetone, and air dried. The material was characterized as K₂IrBr₅(thiazole).

Preparation of MC-51

[IrBr₄(thiazole)₂]^1-: 12 grams of K₃IrBr₆ were added to 60 ml of water in a 200 ml round bottom flask followed by the addition of 6 grams of thiazole. The reaction was initially heterogeneous, but with warming to 85°C and stirring, the iridium salt dissolved. The stoppered flask was maintained at 85° C for 1 hour during which time the color changed from the dark greenish color of IrBr₆ ^3- to a clear bright orange color characteristic of IrBr₄(thiazole)₂ ^-. A fibrous orange precipitate of KIrBr₄(thiazole)₂ started forming near the end of the reaction. After 1 hour at 85° C, the reaction flask was placed in the refrigerator to quench the reaction and precipitate more of the bis-thiazole complex. The reaction flask was removed after about an hour and the volume decreased about 30% with a N₂ flow and then put back into the refrigerator overnight. The precipitated material was filtered off the next morning and washed with about 20 ml of ice cold water and then acetone and air dried. This orange colored material is quite soluble in water and assumed to be the cis isomer.
KIrBr₄(thiazole)₂ was recrystallized by dissolving the material in a minimum amount of warm water (ca. 60° C) and filtering. The filtrate was then decreased in volume by 50% and pure KIrBr₄(thiazole)₂ precipitated with an equal volume of acetone.

Preparation of MC-52

[IrCl₄(H₂O) (tz)]^1-: KIrCl₄(H₂O) (thiazole) was synthesized by the uv-photolysis of K₂IrCl₅(tz) in water. 3.5 grams of K₂IrCl₅(thiazole) were dissolved in 50 ml of DI water in a 50 ml round bottom quartz flask. This was then placed in a water bath (a larger quartz beaker) in order to absorb the infra-red output of the uv-lamp and keep the reaction at ambient temperature (if the reaction gets as high as 50° C, a some of the IrCl₅ (thiazole)^2- will decompose releasing free thiazole). The reaction times were limited to four hour units to keep the reaction from getting too far above room temperature. One of the reaction runs was in D₂O, and ¹H NMR was used to monitor both the disappearance of the starting material K₂IrCl₅(thiazole) and the appearance of the monoaquated product K₂IrCl₄(H₂O)(thiazole). It was found that in ca. 16 hours, 100% of K₂IrCl₅(thiazole) had reacted under our experimental conditions. The main photochemical reaction products are KIrCl₄(H₂O)(thiazole) and KCl, but a few other NMR peaks are observed that are weak and not identified. These unidentified species do not end up in the final product, because they are more soluble in water and in water/acetone solutions than KIrCl₄(H₂O)(thiazole). KIrCl₄(H₂O)(thiazole) itself is very soluble in water, and a volume of acetone about 10 times the volume of water present is needed to precipitate the monoaquo complex. Under these conditions, KCl is also precipitated (but not the unidentified species). If the reaction solution is reduced in volume to near dryness, some of the aquo complex anates reforming K₂IrCl₅(thiazole).
Ag(CF₃COO) (silver trifluoroacetate, AgTFA) was added to the reaction vessel to precipitate the free chloride as AgCl. The solution was filtered after the addition of AgTFA to remove the AgCl, and the filtrate evaporated to near dryness. Either acetone or ethyl alcohol was then added to precipitate KIrCl₄(H₂O) (tz) which was filtered, washed with acetone, and allowed to air dry.
The material that results from using AgTFA to precipitate the free chloride is further purified by passing a concentrated solution of the material through a column of Sephadex. 2.5 grams of material were dissolved in 5 ml water and passed through ca. 25.4 cm (10 inch) of Sephadex G-25 in a 100 ml buret. The material separated into observable bands although there were no clear separations between the bands. The first band collected was small and the color was greenish. This band amounted to about 2 ml. The second band was reddish and amounted to only about 2 ml also. The third band was the major band and with elution with water gave about 20 ml of a reddish brown solution which was evaporated to dryness with N₂, redissolved in a minimum amount of water, and precipitated with ethyl alcohol to give pure KIrCl₄(H₂O) (thiazole).

Preparation of MC-53

[IrCl₄ (4-methylthiazole)₂]^1-: KIrCl₄(4-methylthiazole)₂ was synthesized by the room temperature reaction of excess 4-methylthiazole with K₃IrCl₆. Typically, 5 grams of K₃IrCl₆ and 5 grams of 4-methylthiazole were added together in ca. 100 ml of water in a 250 ml round bottom flask. The mixture was stirred until all the iridium salt dissolved, and then the solution was allowed to stand for 12 days. An orange precipitate slowly formed, and after the 12 days, an equal volume of acetone (100 ml) was added to the flask to precipitate additional orange material. The orange solid was filtered and washed with a 50% water/50% acetone solution and then acetone and air dried. The orange precipitate is not very soluble in water but may be recrystallized by dissolving the orange material in a minimum amount of water at ca. 50° C and precipitating with acetone. The recrystallized orange material was KIrCl₅(4-methylthiazole)₂. KIrCl₄(4-methylthiazole)₂ can also be readily synthesized in aqueous solution at 70° C. Due to its low solubility, the material was assumed to be the trans-isomer.

Preparations of MC-54 and MC-55

[IrCl₅(5-methylthiazole)]^2-: The room temperature reaction of 5-methylthiazole with K₃IrCl₆ in an aqueous media produced the monosubstituted species K₂IrCl₅(5-methylthiazole). 5 grams of K₃IrCl₆ were dissolved in 75 ml of water, and 5 grams of 5-methylthiazole were added. The solution was allowed to remain at ambient temperature for 12 days and then filtered. The volume of the filtrate was reduced with N₂ about 30%, and a volume of acetone 3 times the water volume added to precipitate a pale orange colored solid. This was filtered using a very fine glass filter frit, washed with a 50% acetone/50% water mixture, and then acetone, and air dried. The material was recrystallized by dissolving the material in a minimum amount of water at ambient temperature, filtering the material through a fine frit filter, and then reprecipitating with acetone. The pale orange colored material is the monosubstituted complex K₂IrCl₅(5-methylthiazole).
[IrCl₄(5-methylthiazole)₂]^1-: When the reaction between K₃IrCl₆ and 5-methylthiazole was carried out at 60° C for a period of 8 hours, an orange crystalline material precipitated when the solution was cooled to room temperature. This has been identified as the bis-substituted complex KIrCl₄(5-methylthiazole)₂.

Preparation of MC-56

[IrCl₄(4,5-dimethylthiazole)₂]^1-: The room temperature reaction of 5 grams of K₃IrCl₆ and 5 grams of 4,5-dimethylthiazole resulted in the synthesis of the bis-substituted complex KIrCl₄(4,5-dimethylthiazole)₂. This complex was very soluble in water compared to KIrCl₄(4-methylthiazole)₂, which was assigned the trans-isomer due to its low solubility in water. It is believed that KIrCl₄(4,5-dimethylthiazole)₂ is a cis isomer.

Preparation of MC-57

[IrCl₄(2-bromothiazole)₂]^1-: KIrCl₄(2-bromothiazole)₂ was synthesized by the room temperature reaction of 5 grams of K₃IrCl₅ and 5 grams of 2-bromothiazole in a 5% acetone/95 % water mixture. The mixture was allowed to set for 3 weeks during which time a pale orange material slowly formed and precipitated out of solution. Additional material was precipitated with an equal volume of acetone, filtered, washed with a 50% acetone/50% water mixture, then acetone, and air dried. The material was identified as KIrCl₅(2-bromothiazole)₂.

Preparation of MC-58

[IrCl₄(2-methyl-2-thiazoline)₂]^2-: The reaction of 5 grams of K₃IrCl₆ and 5 grams of 2-methyl-2-thiazoline in a rapidly stirred aqueous solution produced the solid KIrCl₄(2-methylthiazoline)₂ with precipitation using acetone. Small amounts of 2-methyl-2-thiazoline were difficult to remove from the precipitate, but tetrahydrofuran removed the majority of the impurity leaving, only trace amounts.

Preparation of MC-59-64

[IrCl₅L]^2- : An aqueous solution of K₃IrCl₆ was stirred at ambient temperature with an excess of the organic liquid ligand L for several days. The K₂IrCl₅L complex was precipitated by adding the aqueous solution to a water miscible organic solvent, such as acetone or ethyl alcohol. The materials were filtered, washed with a 50:50 volume ratio of water and acetone, then acetone, and air dried.

Preparation of MC-65

[IrCl₅(2,5-dimethylpyrazine)]^2-: The reaction of 5 grams of K₂IrCl₅(H₂O) and 5 grams of 2,5-dimethylpyrazine was conducted in 50 ml of water at 6°C (held at temperature by refrigeration) was conducted over 10 days. The reaction solution was poured into 500 ml of acetone, and the small amount of unreacted K₂IrCl₅(H₂O) remaining was removed through filtration. The orange aqueous filtrate was evaporated to dryness at room temperature and then washed with diethylether and then ethyl alcohol. The material was then added to methyl alcohol and initially dissolved and then reprecipitated to give a very pure solid with the stoichiometry of K₂IrCl₅(2,5-dimethylpyridine) · 1/3CH₃OH.

Preparation of MC-66

[IrCl₅(4-Methylpyrazinium)]^1-: The room temperature reaction between 5 grams of K₃IrCl₆ and 5 grams of N-methylpyrazine iodide in 50 ml of water for ten days yielded the sought coordination complex, which was precipitated with acetone. The complex precipitated was less soluble than the corresponding potassium salt.

Examples

The invention can be better appreciated by reference to the following specific examples:

Examples 1-17

These examples have as their purpose to demonstrate the effectiveness of adding coordination complexes of iridium and at least one organic ligand to AgCl cubic grains. These emulsions demonstrate improved speed, reciprocity, heat sensitivity, and latent image keeping.
This series of emulsions used conventional precipitation techniques employing thioether silver halide ripening agents of the type disclosed in McBride U. S. Patent 3,271,157.
Substrate Emulsion A was prepared as follows: A reaction vessel containing 5.7 l of a 3.9% by weight gelatin solution and 1.2 g 1,8-dihydroxy-3,6-dithiaoctane was adjusted to 46°C, pH of 5.8 and a pAg of 7.51 by addition of a NaCl solution. A 2 M solution of AgNO₃ and a 2 M solution of NaCl were simultaneously run into the reaction vessel with rapid stirring, each at constant flow rates of 249 ml/min while controlling the pAg at 7.51. The emulsion was then washed to remove excess salts. The cubic emulsion grains had an edge length of about 0.38µm.
Substrate Emulsion B was prepared as follows: A reaction vessel containing 8.5 liters of a 2.8% by weight gelatin aqueous solution and 1.9 g 1,8-dihydroxy-3,6-dithiaoctane were adjusted to 68.3°C, pH of 5.8 and pAg of 7.35 by addition of NaCl solution. A 3.75 M solution of AgNO₃ and a 3.75 M solution of NaCl were added simultaneously with rapid stirring. The silver potential was controlled at 7.35 pAg. The emulsion was then washed to remove excess salts. The cubic emulsion grains had an average edge length of 0.6 µm.
Substrate Emulsion C was prepared as follows: A reaction vessel containing 7.15 liters of a 2.7% by weight gelatin solution and 1.9 g 1,8-dihydroxy-3,6-dithiaoctane was adjusted to 68.3°C. A 4 M solution of AgNO₃ and a 4 M solution of NaCl were added simultaneously with flow rates increasing from 48 ml/min. to 83 ml/min. The silver potential was controlled at 7.2 pAg. The emulsion was then washed to remove excess salts. The cubic emulsion grains had an edge length of 0.78 µm.
Substrate Emulsion D was prepared as follows: A reaction vessel containing 4.67 liters of a 2.7% by weight gelatin solution and 1.4 g 1,8-dihydroxy-3,6-dithiaoctane was adjusted to 68.3°C. A 1.35 M solution of AgNO₃ and a 1.8 M solution of NaCl were added simultaneously with flow rates increasing from 54 ml/min. to 312 ml/min. The silver potential was controlled at 7.2 pAg. The emulsion was then washed to remove excess salts. The cubic emulsion grains had an edge length of 1.0 µm.

Example 1

This example illustrates the use of a preformed fine grain silver halide (Lippmann) emulsion as a carrier of the dopant (termed a grain surface modifier), and as a source of the epitaxially deposited silver halide material.
Undoped Lippmann Emulsion L1 was prepared as follows: A reaction vessel containing 4.0 liters of a 5.6% by weight gelatin aqueous solution was adjusted to a temperature of 40°C, pH of 5.8 and a pAg of 8.86 by addition of AgBr solution. A 2.5 molar solution containing 1698.7 grams of AgNO₃ in water and a 2.5 molar solution containing 1028.9 grams of NaBr in water were simultaneously run into the reaction vessel with rapid stirring, each at a constant flow rate of 200 ml/min. The double jet precipitation continued for 3 minutes at a controlled pAg of 8.86, after which the double jet precipitation was continued for 17 minutes during which the pAg was decreased linearly from 8.86 to 8.06. A total of 10 moles of silver bromide (Lippmann bromide) was precipitated, the silver bromide having average grain sizes of 0.05 µm.
Emulsion L5 was prepared exactly as Emulsion L1, except a solution of 0.533 gram of MC-41 in 25 ml water was added at a constant flow rate beginning at 50% and ending at 90% of the precipitation. This triple jet precipitation produced 10 moles of a 0.05 µm grain size emulsion.
Addition of dopant, epitaxially deposited bromide, spectral and chemical sensitization was as follows:
Control Emulsion 1a was prepared as follows: a 50 millimole (mmole) sample of substrate Emulsion B was heated to 40°C and spectrally sensitized by the addition of 14 milligrams of the blue spectral sensitizing dye Dye D, anhydro-5-chloro-3,3'-di(3-sulfopropyl)naphtho[1,2-d]thiazolothiacyanine hydroxide triethylammonium salt.
This was followed by the addition of 0.45 mmole of Emulsion L1. The temperature was raised to 60°C to accelerate recrystallization of the Lippmann bromide, primarily onto corner and edges of the grain. To the emulsion were added 0.13 mg of sodium thiosulfate and 9.5 mg of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene, and the emulsion was held at 60°C until optimal chemical sensitization was achieved. Addition of 1-(3-acetamidophenyl)-5-mercaptotetrazole followed to complete the finishing operation.
Emulsion 1b was prepared and sensitized exactly as Emulsion 1a, except that 0.045 mmole of Emulsion L5 and 0.405 mmole of Emulsion L1 were added during the sensitization process instead of 0.45 mmole of Emulsion L1 alone.
Emulsion 1c was prepared and sensitized exactly as Emulsion 1a, except that 0.0675 mmole of Emulsion L5 and 0.3825 mmole of Emulsion L1 were added during the sensitization process instead of 0.45 mmole of Emulsion L1 alone.
In this way, epitaxially deposited silver chlorobromide regions of Emulsions 1b and 1c were doped with a total of 0.09 mppm and 0.135 mppm of MC-41, respectively.
The emulsions were coated on paper support using sizing methods disclosed in U.S. Patent 4,994,147. Specifically, they were coated at 0.28 gram/m² silver with 0.002 gram/m² of 2,4-dihydroxy-4-methyl-1-piperidinocyclopenten-3-one, 0.02 gram/m² of KCl, 0.78 mg/m² of potassium p-tolylsulfonate, 7.8 mg/m² of sodium p-tolylsulfinate, 1.08 grams/m² yellow dye-forming coupler C2, and with 0.166 gram/m² gelatin. A gelatin protective overcoat layer 1.1 grams/m² was applied along with bis(vinylsulfonylmethyl)ether gelatin hardener.
The coatings were exposed through a step tablet to a 3000°K light source for various exposure times and processed as recommended in "Using KODAK EKTACOLOR RA Chemicals", Publication No. Z-130, cited above. After processing, the Status A reflection densities of each coating were measured.

The photographic parameters obtained for these emulsions are shown in Table 1-I. The results in Table 1-I demonstrate that emulsions with epitaxial regions doped with MC-41 have improved reciprocity and heat sensitivity performance.

Emuls. #	Dopant Complex/ Lippmann Bromide	Nominal Dopant Level (mppm)	Speed for a 0.5" exp.	Speed HIRF (0.031"-0.5")	Heat Sensitivity Δ Speed
1a	none	0	100	-24	20
1b	MC-41	0.09	100	-22	19
1c	MC-41	0.135	98	-18	17

Example 2

Control Emulsion 2a was prepared as follows: a 0.3 mole sample of substrate Emulsion C was heated to 40°C and chemically sensitized by the addition of a colloidal dispersion of gold sulfide followed by digestion at 60°C, and spectrally sensitized by the addition of blue sensitizing dye Dye D.
This was followed by the addition of 1.8 mmoles of KBr. The addition of 1-(3-acetamidophenyl)-5-mercaptotetrazole completed the finishing operation.
Emulsion 2b was prepared and sensitized exactly as Emulsion 2a, except that 0.003 micromole of MC-41 was added prior to the addition of KBr during the finishing operation.
The emulsions were coated, exposed, processed and the sensitometry read as described above in Example 1.
The photographic parameters obtained for these emulsions are shown in Table 2-I. The results in Table 2-I demonstrate that emulsions with epitaxial regions doped with coordination complexes containing iridium and a thiazole ligand have improved reciprocity performance.

Emuls. # Dopant Complex/ Solution Addition Nominal Dopant Level
(mppm) Speed for a 2 sec. exposure Speed HIRF
(0.01" - 2.0")

2a none 0 184 -14

2b MC-41 0.01 183 -11

Examples 3-7

Examples 3-7 demonstrate the effectiveness of adding coordination complexes of iridium and at least one organic ligand into epitaxial regions of cubic AgCl emulsions coated in a tricolor multilayer format. These emulsions demonstrate improved reciprocity, heat sensitivity, and latent image keeping.

Example 3

Control Emulsion 3a was prepared as follows: a 10 mole sample of substrate Emulsion B was heated to 40°C, adjusted to a pH of 5.6, and chemically sensitized by the addition of a colloidal dispersion of gold sulfide followed by digestion at 65°C.
Additional finishing compounds were added in the sequence of 4,4'-bis[(4-chloro-6-o-chloroanilino-s-triazine-2-yl-amino]-2,2'-stilbene disulfonic acid sodium salt, red spectral sensitizing dye anhydro-3-ethyl-9,11-peopentylene-3'-(3-sulfopropyl)thiadicarbocyanine hydroxide (Dye C), 1-(3-acetamidophenyl)-5-mercaptotetrazole, and 0.06 mole of KBr.
Emulsions 3b, 3c and 3d were prepared and sensitized exactly as Emulsion 3a, except that 11.1, 43.5, and 168.0 micromoles of MC-41, respectively, were added prior to the KBr addition during the finishing operation. Doped epitaxial regions were thereby produced.
The emulsions were coated in a conventional tricolor multilayer format along with the blue sensitive and green sensitive emulsions described below.
Blue Emulsion: A high chloride silver halide emulsion was precipitated by equimolar addition of silver nitrate and sodium chloride solutions into a well-stirred reactor containing gelatin peptizer and thioether ripener. The resultant emulsion contained cubic shaped grains of 0.78 µm average edgelength. The emulsion was optimally sensitized by the addition of a colloidal suspension of gold sulfide and heat treated at 60°C, during which time blue spectral sensitizing dye Dye D; 1-(3-acetamidophenyl)-5-mercaptotetrazole and KBr were added.
Green Emulsion: A high chloride silver halide emulsion was precipitated by equimolar addition of silver nitrate and sodium chloride solutions into a well-stirred reactor containing gelatin peptizer and thioether ripener. The resultant emulsion contained cubic shaped grains of 0.30 µm average edgelength. The emulsion was optimally sensitized by the addition of green sensitizing dye anhydro-5-chloro-9-ethyl-5'-phenyl-3'-(3-sulfobutyl)-3-(sulfopropyl)oxacarbocyanine hydroxide, sodium salt (Dye E), a colloidal suspension of gold sulfide, heat digestion followed by the addition of 1-(3-acetamidophenyl)-5-mercaptotetrazole and KBr.

Coupler dispersions were emulsified by methods well known to the art, and the following layers were coated on a polyethylene resin coated paper support, sized as described in U.S. Patent 4,994,147 and pH adjusted as described in U.S. Patent 4,917,994. The polyethylene layer coated on the emulsion side of the support contained a mixture of 0.1% (4,4'-bis(5-methyl-2-benzoxazolyl)stilbene and 4,4'-bis(2-benzoxazolyl) stilbene, 12.5% TiO₂, and 3% ZnO white pigment. The layers were hardened with bis(vinylsulfonylmethyl)ether at 1.95% of the total gelatin weight.

Layer 1: Blue Sensitive Layer
Gelatin	1.530 g/m²
Blue Sensitive Silver	0.280 g Ag/m²
Yellow Dye-Forming Coupler C2	1.080 g/m²
Dibutyl phthalate	0.260 g/m²
2-(2-butoxyethoxy)ethyl acetate	0.260 g/m²
2, 5-Dihydroxy-5-methyl-3-(1-piperidinyl)-2-cyclopenten-1-one	0.002 g/m²
Potassium 2,5-dihydroxy-4-(1-methylheptadecyl)phenylsulfonate	0.009 g/m²

Layer 2: Interlayer
Gelatin	0.753 g/m²
Dioctyl hydroquinone	0.094 g/m²
Dibutyl phthalate	0.282 g/m²
Disodium 4,5 Dihydroxy-m-benzenedisulfonate	0.065 g/m²
Sodium isopropylnaphthylsulfonate (Alkanol XC ™)	0.002 g/m²

Layer 3: Green Sensitive Layer
Gelatin	1.270 g/m²
Green Sensitive Silver	0.263 g Ag/m²
Magenta Dye-Forming Coupler C5	0.389 g/m²
Dibutyl phthalate	0.195 g/m²
2-(2-butoxyethoxy)ethyl acetate	0.058 g/m²
2,3-Dihydro-2,2-dimethyl-7-n-heptadecyl-6-hydroxypyran	0.166 g/m²
Dioctylhydroquinone	0.039 g/m²
Phenylmercaptotetrazole	0.001 g/m²

Layer 4: UV Interlayer
Gelatin	0.630 g/m²
2-[3,5-di(1,1-dimethylpropyl)-2-hydroxyphenyl]-benzotriazole	0.049 g/m²
5-Chloro-2-(3-tert-butyl-2-hydroxy-5-methylphenyl)benzotriazole	0.279 g/m²
Dioctyl hydroquinone	0.080 g/m²
1,4-Cyclohexylenedimethylene bis(2-ethylhexanoate)	0.109 g/m²
Dibutyl phthalate	0.129 g/m²

Layer 5: Red Sensitive Layer
Gelatin	1.087 g/m²
Red Sensitive Silver	0.218 g Ag/m²
Cyan Dye-Forming Coupler C1	0.423 g/m²
Dibutyl phthalate	0.232 g/m²
2-(2-butoxyethoxy)ethyl acetate	0.035 g/m²
Dioctyl hydroquinone	0.004 g/m²

Layer 6: UV Overcoat
Gelatin	0.630 g/m²
2-[3,5-di(1,1-dimethylpropyl)-2-hydroxyphenyl]-benzotriazole	0.049 g/m²
5-Chloro-2-(3-tert-butyl-2-hydroxy-5-methylphenyl)benzotriazole	0.279 g/m²
Dioctyl hydroquinone	0.080 g/m²
1,4-Cyclohexylenedimethylene bis(2-ethylhexanoate)	0.109 g/m²
Dibutyl phthalate	0.129 g/m²

Layer 7: Surface Overcoat
Gelatin	1.076 g/m²
Poly(dimethylsiloxane)	0.027 g/m²
SF-1 Alkanol XC™	0.009 g/m²
SF-2 Sodium perfluorooctylsulfonate	0.004 g/m²
Poly(oxyethylene)tridecanol (Tergitol 15-S-5™)	0.003 g/m²
Tartrazine Yellow	0.018 g/m²
Bis[3-carboxy-1-(4-sulfophenyl)pyrazolin-5-one-(4)]trimethine oxonol, pentasodium salt	0.009 g/m²
Bis[3-acetyl-1-(2,5-disulfophenyl)-2-pyrazolin-5-one-(4)]pentamethine oxonol, pentasodium salt	0.007 g/m²

The multilayer coating described above was evaluated by exposure to a 3000°K color temperature light source through a neutral density step tablet having an exposure range of 0 to 3 logE, and processing as recommended in "Using KODAK EKTACOLOR RA Chemicals", Publication No. Z-130, cited above. The Status A reflection densities of each coating were measured, and the sensitometric response of the red sensitive layer containing the doped epitaxial emulsions of the invention are shown in Table 3-I.

EMUL. #	Dopant Complex	Nominal Dopant Level (mppm)	Speed for a 0.5" exp.	Speed LIRF (0.5"-128")	Speed HIRF (0.031"-0.5")	Contrast RF-Delta Toe density (0.5"-128")
3a	none	0	235	-21.4	-8.0	.066
3b	MC-41	1.11	220	-19.3	-8.0	.063
3c	MC-41	4.35	207	-11.9	-6.3	.036
3d	MC-41	16.8	118	-3.8	-5.9	-.001

The results in Table 3-I demonstrate that emulsions containing epitaxial regions doped at a range of amounts of a coordination complex containing iridium and a thiazole ligand have improved speed reciprocity and contrast reciprocity performance when coated in a tricolor multilayer format.

Example 4

Example 3 was repeated, except that the Layer 3, the green sensitive layer, was replaced with alternate green sensitive layer I.

Alternate Green Sensitive Layer I
Gelatin	1.230 g/m²
Green Sensitive Silver	0.160 g Ag/m²
Magenta Dye-Forming Coupler C6	0.260 g/m²
Tris(2-ethylhexyl)phosphate	0.520 g/m²
2-Butoxy-1-(N,N-dibutylamino)-5-(1,1,3,3-tetramethylbutyl)benzene	0.360 g/m²
ST-4 2,5-Dioctylhydroquinone	0.060 g/m²

The performance observed was similar to that of Example 3.

Example 5

Example 3 was repeated, except that the Layer 3, the green sensitive layer, was replaced with alternate green sensitive layer II.

Alternate Green Sensitive Layer II
Gelatin	1.230 g/m²
Green Sensitive Silver	0.150 g Ag/m²
Magenta Dye-Forming Coupler C7	0.215 g/m²
Dibutyl phthalate	0.097 g/m²
Di (8-methylnononyl)phthalate	0.086 g/m²
1,1-Bis(5-tert-butyl-4-hydroxy-2-methyl-phenyl)butane	0.161 g/m²
Compound C8	0.140 g/m²

The performance observed was similar to that of Example 3.

Example 6

Example 3 was repeated, except that the Layer 3, the green sensitive layer, was replaced with alternate green sensitive layer III.

Alternate Green Sensitive Layer III
Gelatin	1.230 g/m²
Green Sensitive Silver	0.108 g Ag/m²
Magenta Dye-Forming Coupler C9	0.140 g/m²
Tritolyl phosphate	1.119 g/m²
1,1'-Bis(3,3-dimethyl-5,5',6,6'-tetrapropoxyindane)	0.129 g/m²
2-Methyl-1,1-bis(2-hydroxy-3,5-dimethylphenyl)propane	0.054 g/m²
2,6-Dichloro-4-ethoxycarbonylphenyl hexadecanoate	0.097 g/m²
Sodium 3,5-bis{3-[2,4-bis(1,1-dimethylpropyl)phenoxy]propylcarbamoyl}-phenylsulfinate	0.011 g/m²

The performance observed was similar to that of Example 3.

Example 7

Example 3 was repeated, except that the Layer 3, the blue sensitive layer, was replaced with alternate blue sensitive layer I.

Alternate Blue Sensitive Layer I
Gelatin	1.042 g/m²
Blue Sensitive Silver	0.243 g Ag/m²
Yellow Dye-Forming Coupler C10	0.539 g/m²
Bis(3-tert-butyl-2-hydroxy-5-methylphenyl)methane hemiacetate	0.237 g/m²
Sodium 2,5-dihydroxy-4-isooctadecylphenylsulfonate	0.009 g/m²
Dibutyl phthalate	0.301 g/m²
Glycerol	0.162 g/m²

The performance observed was similar to that of Example 3.

Example 8

Example 3 was repeated, except that the Layer 3, the blue sensitive layer, was replaced with alternate blue sensitive layer II.

Alternate Blue Sensitive Layer II
Gelatin	1.042 g/m²
Blue Sensitive Silver	0.243 g Ag/m²
Yellow Dye-Forming Coupler C11	0.645 g/m²
Poly (N-tert-butylacrylamide)	0.538 g/m²
Dibutyl phthalate	0.269 g/m²

The performance observed was similar to that of Example 3.

Example 9

Control Emulsion 9a was prepared as follows: a 10 mole sample of substrate Emulsion A was heated to 40°C, adjusted to a pH of 4.3, and chemically sensitized by the addition of a colloidal dispersion of gold sulfide followed by digestion at 65°C.
Additional finishing compounds were added in the sequence of 1-(3-acetamidophenyl)-5-mercaptotetrazole, 0.12 mole of KBr, and red spectral sensitizing dye Dye C.
Control Emulsions 9b, 9c and 9d were prepared and sensitized exactly as Emulsion 9a, except that 3.7, 11.1, and 22.2 micromoles of K₂IrCl₆ (CD-3), respectively; were added prior to the KBr addition during the finishing operation. Doped epitaxial regions were thereby produced.
Emulsions 9e, 9f and 9g were prepared and sensitized exactly as Emulsion 9a, except that 3.7, 11.1, and 22.2 micromoles of K₂IrCl₅(thiazole) (MC-41), respectively; were added prior to the KBr addition during the finishing operation. Doped epitaxial regions were thereby produced.

The emulsions were coated and evaluated in a conventional tricolor multilayer format, along with blue sensitive and green sensitive emulsions, as described above in Example 3. The sensitometric response of the red sensitive layers containing the doped epitaxial emulsions of the invention are shown in Table 9-I.

Emuls. #	Dopant Complex	Nominal Dopant Level (mppm)	Speed for a 0.5" exp.	Speed LIRF (0.5"-512")	Latent Image Keeping
					Speed	Toe
9a	none	0	130	-7.5	2.8	.01
9b	CD-3	0.37	130	1.6	4.1	.02
9c	CD-3	1.12	119	11.0	4.3	-.017
9d	Cd-3	2.24	109	13.3	-8.4	-.099
9e	MC-41	0.37	131	-0.1	2	.006
9f	MC-41	1.12	132	-0.2	1.7	.008
9g	MC-41	2.24	125	8.2	2.1	.007

The results in Table 9-I demonstrate that emulsions containing epitaxial regions doped at a range of amounts of a coordination complex containing iridium and a thiazole ligand have improved reciprocity, speed LIK and contrast LIK performance relative to an undoped control or a similar K₂IrCl₆ doped control.

Example 10

Control Emulsion 10a was prepared as follows: a 10 mole sample of substrate Emulsion A was heated to 40°C, adjusted to a pH of 4.9 and a pAg of 8.05, and spectrally and chemically sensitized by the addition of spectral sensitizing dye Dye E, a colloidal dispersion of gold sulfide, followed by digestion at 65°C.
Additional finishing compounds were added in the sequence of 1-(3-acetamidophenyl)-5-mercaptotetrazole, 4,4'-bis[(4,6-bis-p-chloroanilino-s-triazine-2-yl)amino]-2,2'-stilbene disulfonic acid sodium salt, 0.16 mole of KBr, and red spectral sensitizing Dye C.
Control Emulsions 10b, 10c and 10d were prepared and sensitized exactly as Emulsion 10a, except that 3.7, 11.2, and 22.4 micromoles of K₂IrCl₆ (CD-3), respectively; were added prior to the KBr addition during the finishing operation. Doped epitaxial regions were thereby produced.
Emulsions 10e, 10f and 10g were prepared and sensitized exactly as Emulsion 10a, except that 3.7, 11.2, and 22.4 micromoles of K₂IrCl₅(thiazole) (MC-41), respectively; were added prior to the KBr addition during the finishing operation. Doped epitaxial regions were thereby produced.

The emulsions were coated and evaluated in a conventional tricolor multilayer format, along with blue sensitive and green sensitive emulsions, as described above in Example 3. The sensitometric response of the red sensitive layers containing the doped epitaxial emulsions of the invention are shown in Table 10-I.

Emuls. #	Dopant Complex	Nominal Dopant Level (mppm)	Speed for a 0.5" exp.	Speed LIRF (0.5"-512")	Latent Image Keeping
					Speed	Toe
10a	none	0	133	-16.2	1.3	.012
10b	CD-3	0.37	131	-2.0	2.5	.01
10c	CD-3	1.12	124	9.3	1.0	-.012
10d	CD-3	2.24	130	13.7	-7.1	-.08
10e	MC-41	0.37	130	-7.2	1.2	.009
10f	MC-41	1.12	132	-8.6	1.6	.006
10g	MC-41	2.24	130	0.7	1.4	.01

The results in Table 10-I demonstrate that emulsions containing epitaxial regions doped at a range of amounts of a coordination complex containing iridium and a thiazole ligand have improved reciprocity and contrast LIK performance relative to an undoped control. Relative to a K₂IrCl₆ doped control, the emulsions of the invention have improved reciprocity, speed LIK and contrast LIK performance.

Example 11

Control Emulsion 11a was prepared as follows: a 10 mole sample of substrate Emulsion B was heated to 40°C, adjusted to a pH of 4.5, and chemically sensitized by the addition of a colloidal dispersion of gold sulfide, followed by digestion at 60 C.
Additional finishing compounds were added in the sequence of blue spectral sensitizing dye Dye D; 1-(3-acetamidophenyl)-5-mercaptotetrazole, and 0.06 mole of KBr.
Control Emulsions 11b and 11c were prepared and sensitized exactly as Emulsion 11a, except that 0.8 and 9.2 micromoles of K₂IrCl₆ (CD-3), respectively; were added prior to the KBr addition during the finishing operation. Doped epitaxial regions were thereby produced.
Emulsions 11d and 11e were prepared and sensitized exactly as Emulsion 11a, except that 0.8 and 9.2 micromoles of K₂IrCl₅(thiazole) (MC-41), respectively; were added prior to the KBr addition during the finishing operation. Doped epitaxial regions were thereby produced.
The emulsions were coated in the conventional tricolor multilayer format described above in Example 3, except that the blue sensitive emulsions of this example were used along with the red sensitive emulsion described below.
Red Emulsion: A high chloride silver halide emulsion was precipitated be equimolar addition of silver nitrate and sodium chloride solutions into a well-stirred reactor containing gelatin peptizer and thioether ripener. The resultant emulsion contained cubic shaped grains of 0.38 mm average edgelength. The emulsion was optimally sensitized by the addition of a colloidal suspension of aurous sulfide, heat digestion followed by the addition of 1-(3-acetamidophenyl)-5-mercaptotetrazole, potassium bromide, KBr, and the red spectral sensitizing dye anhydro-3-ethyl-9,11-neopentalene-3'-(3-sulfopropyl)thiadicarbocyanine hydroxide (Dye I).

The coatings were evaluated as described in Example 3 above. The sensitometric response of the blue sensitive layers containing the doped epitaxial emulsions of the invention are shown in Table 11-I.

EMUL. #	Dopant Complex	Nominal Dopant Level (mppm)	Speed for a 0.5" exp.	Speed LIRF (0.5"-512")	Heat Sensitivity Speed
11a	none	0	140	-28	-3.1
11b	CD-3	0.08	137	-24	-2.8
11c	CD-3	0.92	103	-5	3.5
11e	MC-41	0.08	134	-20	-0.8
11f	MC-41	0.92	110	1	-0.6

The results in Table 11-I demonstrate that emulsions containing epitaxial regions doped at a range of amounts of a coordination complex containing iridium and a thiazole ligand have improved reciprocity and heat sensitivity performance relative to an undoped control or a K₂IrCl₆ doped control.

Example 12

Control Emulsion 12a was prepared as follows: a 10 mole sample of substrate Emulsion D was heated to 40°C, adjusted to a pH of 5.6, chemically sensitized by the addition of a colloidal dispersion of gold sulfide, followed by digestion at 60°C.
Additional finishing compounds were added in the sequence of blue spectral sensitizing dye Dye D; 1-(3-acetamidophenyl)-5-mercaptotetrazole, and 0.1 mole of (Lippmann bromide) Emulsion L1.
Control Emulsions 12b, 12c and 12d were prepared and sensitized exactly as Emulsion 12a, except that 0.8, 4.6 and 9.2 micromoles of K₂IrCl₆ (CD-3), respectively; were added prior to the Lippmann bromide addition during the finishing operation. Doped epitaxial regions were thereby produced.
Emulsions 12e, 12f and 12g were prepared and sensitized exactly as Emulsion 12a, except that 0.8, 4.6 and 9.2 micromoles of K₂IrCl₅(thiazole) (MC-41), respectively; were added prior to the Lippmann bromide addition during the finishing operation. Doped epitaxial regions were thereby produced.

The emulsions were coated and evaluated in the conventional tricolor multilayer format described above in Example 11. The sensitometric response of the blue sensitive layers containing the doped epitaxial emulsions of the invention are shown in Table 12-I.

Emuls. #	Dopant Complex	Nominal Dopant Level (mppm)	Speed for a 0.5" exp.	Speed LIRF (0.5"-512")	Latent Image Keeping
					Speed	Toe
12a	none	0	146	14.5	4.5	.03
12b	CD-3	0.08	150	-2.8	6.3	.05
12c	CD-3	0.46	145	-2.0	26.9	.25
12d	CD-3	0.92	146	-2.2	49.2	.39
12e	MC-41	0.08	147	-1.0	4.8	.04
12f	MC-41	0.46	146	-1.2	4.8	.04
12g	MC-41	0.92	147	2.2	4.5	.04

The results in Table 12-I demonstrate that emulsions containing epitaxial regions doped at a range of amounts of a coordination complex containing iridium and a thiazole ligand have improved speed and reciprocity performance relative to an undoped control. Relative to a K₂IrCl₆ doped control, the emulsions of the invention have improved reciprocity, speed LIK and contrast LIK performance.

Example 13

Control Emulsion 13a was prepared as follows: a 0.3 mole sample of substrate Emulsion C was heated to 40°C and chemically sensitized by the addition of a colloidal dispersion of gold sulfide followed by digestion at 60°C, and spectrally sensitized by the addition of blue spectral sensitizing dye Dye D.
This was followed by the addition of 1-(3-acetamidophenyl)-5-mercaptotetrazole. The addition of 1.8 mmoles of KBr completed the finishing operation.
Emulsions 13b-h were prepared and sensitized exactly as Emulsion 13a, except that 0.126 micromole of the dopant complex listed in Table 13-I for these emulsions were added prior to the addition of KBr during the finishing operation.
The emulsions were coated, exposed, processed and the sensitometry read as described above in Example 1.

The photographic parameters obtained for these emulsions are shown in Table 13-I. The results in Table 13-I demonstrate that emulsions with epitaxial regions doped with coordination complexes containing iridium and either a thiazole derivative or pyrazine derivative ligand have improved reciprocity performance.

Emuls. #	Dopant Complex/ Solution addition	Nominal Dopant Level (mppm)	Contrast HIRF-delta toe dens. (.02-2")	Contrast LIRF-delta toe dens. (2-100")	Speed HIRF (.02-2")
13a	none	0	0.062	0.078	-7
13b	MC-54	0.42	0.051	0.012	-5
13c	MC-52	0.42	0.056	0.059	-4
13d	MC-57	0.42	0.049	0.069	-1
13e	MC-60	0.42	0.004	0.008	-1
13f	MC-65	0.42	0.057	0.055	-3
13g	MC-62	0.42	0.006	0.008	0
13h	MC-56	0.42	0.053	0.054	-4

Example 14

Control Emulsion 14a was prepared as follows: a 0.3 mole sample of substrate Emulsion C was heated to 40°C and chemically sensitized by the addition of a colloidal dispersion of gold sulfide followed by digestion at 60°C, and spectrally sensitized by the addition of blue spectral sensitizing dye Dye D.
This was followed by the addition of 1-(3-acetamidophenyl)-5-mercaptotetrazole. The addition of 1.8 mmoles of KBr completed the finishing operation.
Emulsions 14b-d were prepared and sensitized exactly as Emulsion 14a, except that 0.126 micromole of the dopant complex listed in Table 14-I for these emulsions were added prior to the addition of KBr during the finishing operation.
The emulsions were coated, exposed, processed and the sensitometry read as described above in Example 1.

The photographic parameters obtained for these emulsions are shown in Table 14-I. The results in Table 14-I demonstrate that emulsions with epitaxial regions doped with coordination complexes containing iridium and either a thiazole derivative or pyrazine derivative ligand have improved reciprocity performance.

Emuls. #	Dopant Complex/ Solution Addition	Nominal Dopant Level (mppm)	Contrast HIRF-delta toe density (0.01" - 2.0")
14a	none	0	0.078
14b	MC-53	0.42	0.053
14c	MC-63	0.42	0.064
14d	MC-51	0.42	-0.043

Example 15

Control Emulsion 15a was prepared as follows: a 0.3 mole sample of substrate Emulsion C was heated to 40°C and chemically sensitized by the addition of a colloidal dispersion of gold sulfide followed by digestion at 60°C, and spectrally sensitized by the addition of blue spectral sensitizing dye Dye D.
This was followed by the addition of 1-(3-acetamidophenyl)-5-mercaptotetrazole. The addition of 1.8 mmoles of KBr completed the finishing operation.
Emulsions 15b and 15c were prepared and sensitized exactly as Emulsion 15a, except that 0.126 micromole of the dopant complex listed in Table 15-I for these emulsions were added prior to the addition of KBr during the finishing operation.
The emulsions were coated, exposed, processed and the sensitometry read as described above in Example 1.
The photographic parameters obtained for these emulsions are shown in Table 15-I. The results in Table 15-I demonstrate the effectiveness of coordination complexes containing iridium and a pyrazine derivative ligand to increase contrast when doped into the epitaxial regions of the emulsion.

Emuls. # Dopant Complex/Solution Addition Nominal Dopant Level (mppm) Contrast @ Density=1.0

15a none 0 2.80

15b MC-66 0.42 4.67

15c MC-59 0.42 4.38

Example 16

Control Emulsion 16a was prepared as follows: a 0.3 mole sample of substrate Emulsion C was heated to 40°C and chemically sensitized by the addition of a colloidal dispersion of gold sulfide followed by digestion at 60°C, and spectrally sensitized by the addition of blue spectral sensitizing dye Dye D.
This was followed by the addition of 1-(3-acetamidophenyl)-5-mercaptotetrazole. The addition of 1.8 mmoles of KBr completed the finishing operation.
Emulsions 16b was prepared and sensitized exactly as Emulsion 16a, except that the dopant complex listed in Table 16-I for these emulsions were added prior to the addition of KBr during the finishing operation.
The emulsions were coated, exposed, processed and the sensitometry read as described above in Example 1.
The photographic parameters obtained for these emulsions are shown in Table 16-I. The results in Table 16-I demonstrate the effectiveness of coordination complexes containing iridium and either a pyrazine derivative ligand to decrease contrast when doped into the epitaxial regions of the emulsion.

Emuls. # Dopant Complex/-Solution Addition Nominal Dopant Level (mppm) Contrast @Density=1.0

16a none 0 2.80

16b MC-61 0.42 2.53

16c MC-14j 10.0 2.58

Example 17

Control Emulsion 17a was prepared as follows: a 0.3 mole sample of substrate Emulsion C was heated to 40°C and chemically sensitized by the addition of bis (1,4,5-triethyl-1,2,4-triazolium-3-thiolate gold(I) tetrafluroborate followed by digestion at 60°C, and spectrally sensitized by the addition of blue dye Dye D.
This was followed by the addition of sodium thiosulfate, 1-(3-acetamidophenyl)-5-mercaptotetrazole, and sodium bromide to completed the finishing operation.
Emulsions 17b and 17c prepared and sensitized exactly as Emulsion 17a, except that 0.31 micromoles of K₂IrCl₆ (CD-3) and K₂IrCl₅(thiazole) (MC-41), respectively; were added prior to the addition of the dye during the finishing operation. Doped epitaxial regions were thereby produced.
The emulsions were coated, exposed, processed and the sensitometry read as described above in Example 1. The photographic parameters obtained for these emulsions are shown in Table 17-I.

Emuls. # Dopant Complex/Solution Addition Nominal Dopant Level (mppm) Speed for a 1 sec. exposure Speed HIRF (0.0001" - 1.0")

17a none 0 156 -20

17b CD-3 0.31 154 -5

17c MC-41 0.31 164 -3
The results in Table 17-I demonstrate the effectiveness of a coordination complex containing iridium and a thiazole ligand doped into the epitaxial region of the emulsion to increase speed and improve reciprocity relative to either an undoped control emulsion or an K₂IrCl₆ doped control emulsion.

Claims

A photographic silver halide emulsion comprised of radiation sensitive composite silver halide grains including host grain portions accounting for at least 50 percent of total silver and surface portions epitaxially deposited on the host grain portions
CHARACTERIZED IN THAT the epitaxially deposited surface portions on the host grain portions exhibit a face centered cubic crystal lattice structure containing a hexacoordination complex of a metal from periods 4, 5 and 6 of groups 3 to 14 inclusive of the periodic table of elements in which one or more organic ligands each containing at least one carbon-to-carbon bond, at least one carbon-to-hydrogen bond or at least one carbon-to-nitrogen-to-hydrogen bond sequence occupy up to half the metal coordination sites in the coordination complex and at least half of the metal coordination sites in the coordination complex are provided by halogen or pseudohalogen ligands, with the proviso that when the host grain portions comprise cubic silver chloride grains, the hexacoordination complex of a metal contained in the epitaxially deposited surface portion is other than K₂[IrCl₅(pyrazine)] or K₄[Ir₂Cl₁₀ (pyrazine)].
A photographic silver halide emulsion according to claim 1 further characterized in that the epitaxially deposited surface portions are located principally adjacent at least one of edges and corners of the host grain portions.
A photographic silver halide emulsion according to claim 1 or 2 further characterized in that the composite silver halide grains contain at least 90 mole percent chloride, from 0 to 10 mole percent bromide and from 0 to 2 mole percent iodide, with the epitaxially deposited surface portions containing a higher concentration of halides other than chloride than the host grain portions.
A photographic silver halide emulsion according to any one of claims 1 to 3 inclusive further characterized in that the organic ligands are selected from among substituted and unsubstituted aliphatic and aromatic hydrocarbons, amines, phosphines, amides, imides, nitriles, aldehydes, ethers, ketones, organic acids, sulfoxides, and aliphatic and aromatic heterocycles including one or a combination of chalcogen and pnictide hetero ring atoms.
A photographic silver halide emulsion according to any one of claims 1 to 4 inclusive further characterized in that the metal ion dopant is chosen from among Group VIII metal dopants.
A photographic silver halide emulsion according to any one of claims 1 to 5 inclusive further characterized in that the hexacoordination complex is an anionic complex satisfying the formula (I)
[MX_xY_yL_z] or (II)
[MZ₅L'Z'₅M'] where
M and M' are independently selected group 8 or 9 metals;
X is Cl, Br or CN;
x is 3 to 5;
Y is H₂O;
y is 0 or 1;
L is an organic ligand containing at least one carbon-to-carbon bond, at least one carbon-to-hydrogen bond or at least one carbon-to-nitrogen-to-hydrogen bond sequence;
L' is an organic bridging ligand containing at least one carbon-to-carbon bond, at least one carbon-to-hydrogen bond or at least one carbon-to-nitrogen-to-hydrogen bond sequence;
z is 1 or 2; and
Z and Z' are independently selected from among X, Y and L, with the proviso that in at least three occurrences of each of Z and Z' they are X and in zero or 1 occurrence of each of Z and Z' they are H₂O.
A photographic emulsion according to claim 6 further characterized in that L is a thiazole, thiazoline or pyrazine.
A photographic silver halide emulsion according to claims 6 or 7 further characterized in that the metal forming the coordination complex is present in a concentration ranging from 10^-9 to 10^-3 gram-atom per silver mole, based on total silver.
A photographic emulsion according to any one of claims 6 to 8 inclusive further characterized in that M in formula (I) and at least one of M and M' in formula (II) is iridium and iridium is present in a concentration of 10^-9 to 10^-5 gram atom per silver mole.
A photographic emulsion according to any one of claims 6 to 8 inclusive further characterized in that M and M' are selected from the group 8 metals iron and ruthenium and the group 8 metals are present in a concentration of from 10^-7 to 10^-3 gram atom per silver mole.