EP1754267A1 - Organometallic compounds and devices made with such compounds - Google Patents

Abstract

The present invention is generally directed to organometallic compounds having Formula (I), Formula (II), or Formula (III) and devices having a layer including at least one of these compounds: (I), (II), (III) wherein: L1 is selected from an aryl-N-heterocycle ligand and a heteroaryl-N-heterocycle ligand , L2 is an anionic ligand , L3 is a nonionic ligand , L4 is selected from L1 and L2 M is a metal selected from Re, Ru, Os, Rh, Ir, Pd, Pt, and Au Fw is a moiety capable of bearing at least two (L4 -Ye) groups Y is a group selected from alkylene, heteroalkylene, alkenylene, heteroalkenylene, and alkynylene a is selected from 1and 2 b is selected from 0 and 1 c is selected from 0, 1, and 2 d is selected from 0 and an integer from 1 through 8 e is selected from 0 and 1 f is selected from 0 and 1 g is an integer from 1 through 4, and h is selected from 1and 2, with the proviso that a, b, and c are selected such that the metal is tetracoordinate when M is Au, Pd, or Pt, and the metal is hexacoordinate when M is Re, Ru, Os, Rh, or Ir, and with the proviso that when f = 0, then e = 0 and there is at least one substituent R1 on at least one ligand, wherein R1 is solvent-solubilizing. .

Description

TITLE ORGANOMETALLIC COMPOUNDS AND DEVICES MADE WITH SUCH COMPOUNDS BACKGROUND OF THE INVENTION Field of the Invention This invention relates to organometallic compounds, and more particularly to electrically active organometallic compounds. It also relates to electronic devices in which an active layer includes at least one such organometallic compound. This application claims priority to United States Provisional

Application No. 60/545,596 filed June 9, 2004. Description of the Related Art Organic electronic devices that emit light, such as light-emitting diodes that make up displays, are present in many different kinds of electronic equipment. In all such devices, an organic active layer is sandwiched between two electrical contact layers. At least one of the electrical contact layers is light-transmitting so that light can pass through the electrical contact layer. The organic active layer emits light through the light-transmitting electrical contact layer upon application of electricity across the electrical contact layers. It is well known to use organic electroluminescent compounds as the active component in light-emitting diodes. Simple organic molecules such as anthracene, thiadiazole derivatives, and coumarin derivatives are known to show electroluminescence. Semiconductive conjugated polymers have also been used as electroluminescent components, as has been disclosed in, for example, Friend et al., U.S. Patent 5,247,190, Heeger et al., U.S. Patent 5,408,109, and Nakano et al., Published European Patent Application 443 861. Complexes of 8-hydroxyquinolate with trivalent metal ions, particularly aluminum, have been extensively used as electroluminescent components, as has been disclosed in, for example, Tang et al., U.S. Patent 5,552,678. Burrows and Thompson have reported that fac-tris(2- phenylpyridine) iridium can be used as the active component in organic light-emitting devices. (Appl. Phys. Lett. 1999, 75, 4.) The performance is maximized when the iridium compound is present in a host conductive material. Thompson has further reported devices in which the active layer is poly(N-vinyl carbazole) doped with fac-tris[2-(4',5'- difluorophenyl)pyridine-C'²,N]iridium(lll). (Polymer Preprints 2000, 41 (1 ), 770.) Electroluminescent iridium complexes having fluorinated phenylpyridine, phenylpyrimidine, or phenylquinoline ligands have been disclosed in published application WO 02/02714. However, there is a continuing need for electroluminescent compounds. SUMMARY OF THE INVENTION The present invention is directed to a compound having Formula I, Formula II, or Formula III

,IAIAM ⁴— Y_e -}- (FW)_f (I)

wherein: L¹ is selected from an aryl-N-heterocycle ligand and a heteroaryl-N- heterocycle ligand L² is an anionic ligand L³ is a nonionic ligand L⁴ is selected from L¹ and L² M is a metal selected from Re, Ru, Os, Rh, Ir, Pd, Pt, and Au FW is a moiety capable of bearing at least two (L⁴ -Y_e) groups Y is a group selected from alkylene, heteroalkylene, alkenylene, heteroalkenylene, and alkynylene a is selected from 1 and 2 b is selected from 0 and 1 c is selected from 0, 1 , and 2 d is selected from an integer from 1 through 8 e is selected from 0 and 1 f is selected from 0 and 1 , g is an integer from 1 through 4, and h is selected from land 2. with the proviso that a, b, and c are selected such that the metal is tetracoordinate when M is Au, Pd, or Pt, and the metal is hexacoordinate when M is Re, Ru, Os, Rh, or Ir, and with the proviso that when f = 0, then e = 0 and there is at least one substituent R¹ on at least one ligand, wherein R¹ is solvent-solubilizing. In another embodiment, a composition comprises at least one of the above compounds of Formula I, II, or 111. In another embodiment, there are provided electronic devices containing at least one active layer comprising at least one invention compound. In another embodiment, there are provided organic light emitting diodes (OLEDs) containing at least one active layer including at least one invention compound. In another embodiment, there are provided electroluminescent devices containing at least one active layer including at least one invention compound. In further embodiments, there are provided methods for improving solution processability of electroluminescent organometallic compounds. In one embodiment, such methods are performed by assembling monometallic groups into polymetallic compounds by covalently attaching at least two monometallic groups to a framework structure, wherein the monometallic groups are either directly attached to the framework structure through a ligand or indirectly attached through a linker, thereby improving solution processability. In one embodiment, such methods are performed by attaching at least one solvent-solubilizing substituent to at least one ligand of an organomonometallic compound. The foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as defined in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated by way of example and not limitation in the accompanying figures. Figures 1-4 show examples of some compounds of the invention. Figure 5 is a schematic diagram of one illustrative example of a light-emitting device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Provided are compounds of the above Formulae I, II, and III, compositions containing these compounds and electronic devices containing at least one active layer comprising one of the above Formulae. In one embodiment, there are provided organic light emitting diodes (OLEDs) containing at least one active layer including at least one compound of the above Formulae. In another embodiment, there are provided photoactive devices containing at least one active layer including a compound of the above Formulae. In the preparation of organic electronic devices, it is frequently desirable to form one or more layers using solution-processing techniques. In the field of OLEDs, the formation of highly efficient and long-lived multilayer solution processed devices is a difficult challenge. Some of the issues encountered in this area are thermal and morphological stability and film-forming ability of the organic materials. Of particular relevance is the solubility and film-forming ability of materials used in the active layer, (e.g., emissive) layer. In certain embodiments, the ultimate device performance is dependent on the quality of the deposited film. In one OLED embodiment, the emissive layer comprises a host transport material into which the electroluminescent material is doped at <20 wt %. In one embodiment there is excellent miscibility between the host and electroluminescent material and a quality film may be deposited by a liquid deposition technique. The compounds of the invention have Formula I, Formula II, or Formula III, described above. M is a metal selected from Re, Ru, Os, Rh, Ir, Pd, Pt, and Au. Pd, Pt, and Au have a +2 oxidation state and are typically tetra-coordinate. The L¹ ligand, described below, occupies two of the coordination positions. The other two are occupied by L⁴ and, when L⁴ is monodentate, also by L³. Re, Ru, Os, Rh, and Ir have a +3 oxidation state and are typically hexacoordinate. The L¹ ligand, described below, occupies two or four of the coordination positions. The other positions are occupied by L⁴ and, in some cases, combinations of L² and L³. In one embodiment, M is selected from Os, Ir, and Pt. L¹ is selected from an aryl-N-heterocycle ligand and a heteroaryl-N- heterocyle ligand. The ligand has an aromatic or heteroaromatic ring joined to a N-heteroaromatic ring by a single bond. The aromatic or heteroaromatic ring may comprise a single ring or a fused ring system. Examples of aromatic rings include, but are not limited to phenyl, naphthyl, and anthracenyl. Examples of heteroaromatic rings include, but are not limited to, rings derived from thiophene, dithiole pyridine. The N- heteroaromatic ring may comprise a single ring or fused ring system. Examples of N-heteroaromatic groups include, but are not limited to, pyridine, pyrazine, pyrimidine, and quinolines. In one embodiment, L¹ is selected from a phenyl-pyridine, phenyl-pyrimidine, phenyl-quinoline, bipyridine and thienyl-pyridine. Ligand L¹ is coordinated to the metal by two points of attachment and is a monoanionic, bidentate ligand. The two points of attachment are through the nitrogen atom of the N- heteroaromatic ring and to a carbon of the aromatic or heteroaromatic ring. L² is a monoanionic ligand. L² can be monodentate, bidentate or tridentate. Examples of monodentate L² ligands include, but are not limited to, H- ("hydride") and ligands having C, O or S as coordinating atoms. Coordinating groups include, but are not limited to alkoxide, carboxylate, thiocarboxylate, dithiocarboxylate, sulfonate, thiolate, nitrile, aryl, carbamate, dithiocarbamate, thiocarbazone anions, sulfonamide anions, and the like. In some cases, ligands discussed below as bidentate, such as β-enolates and phosphinoakoxides, can act as monodentate ligands. The monodentate ligand can also be a coordinating anion such as halide, nitrate, sulfate, hexahaloantimonate, and the like. These ligands are generally available commercially. The bidentate L² ligands generally have N, O, P, or S as coordinating atoms and form 5- or 6-membered rings when coordinated to the metal. Suitable coordinating groups include amino, imino, amido, alkoxide, carboxylate, phosphino, thiolate, and the like. Examples of suitable parent compounds for these ligands include, but are not limited to ?-dicarbonyls ( ?-enolate ligands), and their N and S analogs; amino carboxylic acids (aminocarboxylate ligands); pyridine carboxylic acids (iminocarboxylate ligands); salicylic acid derivatives (salicylate ligands); hydroxyquinolines (hydroxyquinolinate ligands) and their S analogs; and phosphinoalkanols (phosphinoalkoxide ligands). The ?-enolate ligands generally have the FormulalV: R² \ (-i)

where R² is the same or different at each occurrence. The R² groups can be hydrogen, halogen, substituted or unsubstituted alkyl, aryl, alkylaryl or heterocyclic groups. Adjacent R² and R³ groups can be joined to form five- and six-membered rings, which can be substituted. In one embodiment, R² groups are selected from C_n(H+F)_2n+-i , -C₆H₅, C-C4H3S, and C-C4H3O, where n is an integer from 1 through 20. The R³ group can be H, substituted or unsubstituted, alkyl, aryl, alkylaryl, heterocyclic groups or fluorine. Examples of suitable ?-enolate ligands include the compounds listed below. The abbreviation for the ?-enolate form is given below in brackets. 2,4-pentanedionate [acac] 1 ,3-diphenyl-1 ,3-propanedionate [Dl] 2,2,6,6-tetramethyl-3,5-heptanedionate [TMH] 4,4,4-trifluoro-1-(2-thienyl)-1 ,3-butanedionate [TTFA] 7,7-dimethyl-1 ,1 ,1 ^^.S^-heptafluoro^.β-octanedionate [FOD] 1 ,1 ,1 ,3,5,5,5-heptafluoro-2,4-pentanedionate [F7acac] 1 ,1 ,1 ,5,5,5-hexafluoro-2,4-pentanedionate [F6acac] 1 -phenyI-3-methyl-4-/^'-butyryl-pyrazolinonate [FMBP] The ?-dicarbonyl parent compounds, are generally available commercially. The parent compound 1 ,1 ,1 ,3,5,5,5-heptafluoro-2,4- pentanedione, CF₃C(O)CFHC(O)CF₃ , can be prepared using a two-step synthesis, based on the reaction of perfluoropentene-2 with ammonia, followed by a hydrolysis step according to the procedure published in Izv. AN USSR. Ser. Khim. 1980, 2827. This compound should be stored and reacted under anhydrous conditions as it is susceptible to hydrolysis. The hydroxyquinolinate ligands can be substituted with groups such as alkyl or alkoxy groups which may be partially or fully fluorinated.

Examples of suitable hydroxyquinolinate ligands include (with abbreviation provided in brackets): 8-hydroxyquinolinate [8hq] 2-methyl-8-hydroxyquinolinate [Me-8hq] 10-hydroxybenzoquinolinate [10-hbq] The parent hydroxyquinoline compounds are generally available commercially. Phosphino alkoxide ligands generally have Formula V:

R⁵ P- [C(R⁴)₂]_φ — -Q^ (V) R>

where R⁴ can be the same or different at each occurrence and is selected from H and C_n(H+F) _n+i , R⁵ can be the same or different at each occurrence and is selected from C_n(H+F)_2n+1 and C₆(H+F)₅, or C₆H₅._m(R6)_m, R6 = CF₃, C₂F₅, π-C₃F₇, /-C₃F₇, C₄F₉, CF₃SO_2> and φ is 2 or 3; m is 0 or an integer from 1 through 5; and n is an integer from 1 through 20. Examples of suitable phosphino alkoxide ligands include (with abbreviation provided in brackets): 3-(diphenylphosphino)-1 -oxypropane [dppO]; 1 ,1-bis(trifluoromethyl)-2-(diphenylphosphino)-ethoxide [tfmdpeO]; 1 ,1-bis(trifluoromethyl)-2-(bis(3'5'- ditrifluoromethylphenyl)phosphino)ethoxide [PO-2]; 1 ,1-bis(trifluoromethyl)-2-(bis(4'- trifluoromethylphenyl)phosphino)ethoxide [PO-3]; and 1 ,1-bis(trifluoromethyl)-2- (bis(pentafluorophenyl)phosphino)ethoxide [PO-4]. Some of the parent phosphino alkanol compounds are available commercially, or can be prepared using known procedures, such as, for example, the procedure reported for tfmdpeO in Inorg. Chem. 1985, v.24, p.3680 or in J. Fluorine Chem. 2002, 117, 121 In one embodiment, L² is a ligand coordinated through a carbon atom which is part of an aromatic group. The ligand can have Formula VI: Ar[-(CH₂)_q-Q]_p (VI)

wherein Ar is an aryl or heteroaryl group, Q is a group having a heteroatom capable of coordinating to a metal, q is 0 or an integer from 1 through 20, p is an integer from 1 through 5, and further wherein one or more of the carbons in (CH₂)_q can be replaced with a heteroatom and one or more of the hydrogens in (CH₂)_q can be replaced with D or F. In one embodiment^ is selected from N(R⁷)₂, OR⁷, SR⁷, and P(R⁸)₂, wherein R⁷ is the same or different at each occurrence and is H, C_nH_2n+1or C_n(H+F) _n+1 and R⁸ is the same or different at each occurrence and is selected from H, R⁷, Ar and substituted Ar. In one embodiment, Ar is phenyl, q is 1 , Q is P(Ar)₂, and p is 1 or 2. Tridentate L² ligands are similar to bidentate ligands, but include an additional nonionic group capable of coordinating to the metal. Examples of nonionic groups include, but are not limited to amino, imino, and phosphino groups. The L³ ligand is non-ionic and can be monodentate or bidentate. Examples of L³ ligands include, but are not limited to CO, mono- and bidentate phosphine ligands, isonitriles, imines, and diimines. The phosphine ligands can have Formula VII or Formula Vlll

PAr₃ (VII) Ar₂P - Z - P Ar₂ (Vlll)

where Ar represents an aryl or heteroaryl group and Z represents an alkylene, heteroalkylene, arylene or heteroarylene group. The Ar group can be unsubstituted or substituted with alkyl, heteroalkyl, aryl, heteroaryl, halide, carboxyl, sulfoxyl, or amino groups. The phosphine ligands are generally available commercially. L⁴ is an anionic ligand. In Formula I, when e = 1 , and in Formulae

II and III, L⁴ is also attached to a central framework. L⁴ can be an aryl N- heterocycle, which is the same as or different from L . L⁴ can be an anionic ligand, as described above for L². It will be understood that in Formula I, when e = 1 , and in Formulae II and III, L⁴ must be capable of both coordination to the metal and attachment to the central framework. In this case, L⁴ cannot be hydride, for example. In one embodiment, the solution processability of an electrically active organometallic compound is increased by assembling monometallic groups into polymetallic compounds. Fw represents a chemical framework onto which one, or more than one, metal unit can be attached. A myriad of possible framework structures exist for use in constructing invention compounds. The number of metal units that may be attached to the framework structure is shown as "d" in Formula I, as "g" in Formula II, and as "h" in Formula III. The number varies depending on the type of framework structure, the nature of the L⁴ ligand, and the nature of the other ligands on the metal. In some embodiments, the number of metal units attached to the framework varies from two up to about six. In other embodiments, the number of metal units attached to the framework can be greater than six, provided that frameworks with branching points are employed. In one embodiment, the framework structure is a hydrocarbyl moiety having at least one aryl ring. Exemplary framework structures containing aryl rings are set forth below, wherein " " represents a point of attachment for a metal unit:

In another embodiment, the framework structure is a cyclic aliphatic moiety such as a cyclohexyl ring. A variety of inorganic materials may also be employed as framework structures in invention polymetallic complexes. In one embodiment, the invention compound is a siloxane. In another embodiment, the framework structure is a silsesquioxane. An exemplary silsesquioxane having an alkynylene linker is set forth below:

wherein " " represents a point of attachment for a metal unit. In the above structure, Si-Si denotes Si-O-Si. Any of the above framework structures can be further substituted.

Examples of substitutuents include, but are not limited to, groups such as alkyl, aryl, heteroalkyl, heteroaryl, alkoxy, and aryloxy, where such groups may be partially or fully fluorinated. By "fluorinated" it is meant that one or more hydrogens in the groups is replaced by fluorine. Y represents an optional linking group between the framework structure and the attaching ligand L⁴. If utilized in invention compounds, linkers can be any group that does not detrimentally affect the desired properties of the metal compound. Examples include, but are not limited to O, S, alkylene, heteroalkylene, alkenylene, heteroalkenylene, alkynylene, and heteroalkynylene. For example, for light-emitting uses, the linking group should not perturb the emission characteristics of each electroluminescent metal center attached to the framework. The linkers can be chosen so that each metal group is oriented in space so as to optimize electroluminescent efficiency. In some embodiments, the linker is an alkylene, alkenylene, or alkynylene moiety having from 1 to 6 carbons. In one embodiment, the solution processability is increased by incorporating at least one solvent solubilizing substituent, R¹, on at least one aryl or heteroaryl group. In one embodiment R¹ is selected from alkyl, fluoroalkyl, aryl, fluoroaryl, alkylaryl, alkoxy, aryloxy, fluoroalkoxy, fluoraryloxy, and their hetero-analogs. In one embodiment R is selected from phenyl, fluorophenyl, alkylphenyl, fluoroalkylphenyl, alkoxy phenyl, and fluoroalkoxyphenyl. In one embodiment, R¹ is an aryl substituted aryl group. In one embodiment, R¹ is a tetraphe-nyl phenyl group. The structures set forth below depict exemplary ?-enolates as L⁴ ligands linked to aryl framework structures via a CH₂ linking group. Also shown below is an example of a ?-enolate ligand attached to a cyclohexyl framework structure via an oxygen atom.

Exemplary invention compounds having Ir as the metal, phenylpyridine or phenyl-quinoline as L¹ , ?-enoIates as L⁴ ligands, and an aryl ring as Fw are set forth in Figure 1. In one embodiment, the compound has Formula I, e = f = 0, and there is at least one substituent, R¹ , on at least one ligand, where R¹ is solvent-solubilizing. In one embodiment R¹ is selected from alkyl, fluoroalkyl, aryl, fluoroaryl, alkylaryl, alkoxy, aryloxy, fluoroalkoxy, fluoraryloxy, and their hetero-analogs. In one embodiment R¹ is selected from phenyl, fluorophenyl, alkylphenyl, fluoroalkylphenyl, alkoxy phenyl, and fluoroalkoxyphenyl. In one embodiment R¹ is an aryl-substituted aryl group. Exemplary invention compounds having Formula I where e = f = 0, with Ir as the metal and phenyl-pyridine as L¹ are given in Figures 2-4. The organometallic compounds of the invention are non-ionic. They can be formed into films by any conventional means. They can be formed into pure films, or they can be combined with other materials in films. The lower molecular weight compounds can, in some cases, be sublimed intact. Thin films of these materials can be obtained via vacuum deposition. However, it is frequently advantageous to deposit the compounds by solution processing. Any known liquid deposition technique can be used. The liquid medium for solution processing the new organometallic compounds can be any organic or partially organic liquid in which the compounds can be dissolved or dispersed. In general, the liquid medium is non-aqueous. Examples of suitable organic liquids which can be used as the liquid medium include, but are not limited to, toluene, fluorinated toluenes, xylenes, fluorinated xylenes, chlorinated hydrocarbons, ethylacetate, and 4-hydroxy-4-methyl-2-pentanone, and mixtures thereof. The new organometallic compounds may be synthesized in a variety of ways using synthetic organic and organometallic techniques well-known to those skilled in the art. Some exemplary syntheses are set forth below for compounds where M is Ir. Analogous reactions can be carried out for other metals.

Step A

STEP B

Steps A and B depict the synthesis of an aryl framework structure bearing 4 suitable bidentate, monoanionic ligands L⁴. Reaction of 2,4- pentanedione with 1 ,2,4,5-tetra-bromomethylbenzene in the presence of a strong base such as lithium diisopropylamide ("LDA") affords 1 ,2,4,5-tetra- (3,5-dioxo-hexyl)benzene. This framework structure bears four ?-dicarbonyl moieties, which, after deprotonation to form ?-dienolates, are suitable for coordinating up to four monometallic groups. This is accomplished as shown, for example, in Step B. The framework structure with fourβ-dicarbonyl moieties is reacted with NaH to produce the acetylacetonate moieties, L⁴, which then react with a precursor Ir complex to form an example of an invention compound. The precursor organometallic complex can be prepared via an intermediate dimer, such as

where L is the same or different and is typically a ligand of type L¹ , and Z is Cl or OR⁹, where R⁹ is H, CH₃, or C₂Hs. The iridium dimers can generally be prepared by first reacting iridium trichloride hydrate with the ligands L¹ and optionally adding NaOR⁹. Compounds having Formula I, where e = f = 0, a = 2, and L⁴ = L¹ can be prepared by the reaction of iridium trichloride hydrate, an excess of ligand, and silver trifluoroacetate. The aryl-N-heterocycle and heteroaryl-N-heterocyle ligands can generally be prepared using the Suzuki coupling of the component groups, as described in O. Lohse, P.Thevenin, E. Waldvogel Synlett, 1999, 45-48. The compounds of the invention, can be isolated, purified, and fully characterized by elemental analysis, ¹ H and ¹⁹F NMR spectral data, and, for suitable crystalline compounds, single crystal X-ray diffraction. In some cases, mixtures of isomers are obtained. Often the mixture can be used without isolating the individual isomers. If individual isomers are desired they are often separable by liquid chromatography on silica or alumina media using standard techniques. Electronic Device Another embodiment is a new organic electronic device comprising at least one layer comprising the above organometallic compound. The organometallic compound can be in a separate layer or can be combined with other active or inactive materials in the device. An illustration of one type of organic electronic device structure is shown in Figure 5. The device 100 has an anode layer 1 10 and a cathode layer 150. Adjacent to the anode is a layer 120 comprising hole transport material. Adjacent to the cathode is a layer 140 comprising an electron transport material. Between the hole transport layer and the electron transport layer is the photoactive layer 130. Depending upon the application of the device 100, the photoactive layer 130 can be a light-emitting layer that is activated by an applied voltage (such as in a light-emitting diode or light-emitting electrochemical cell, light-emitting display), a layer of material that responds to radiant energy and generates a signal with or without an applied bias voltage (such as in a photodetector). Electronic devices that have utility for the compounds disclosed herein include: (1 ) devices that convert electrical energy into radiation (e.g., a light- emitting diode, light-emitting diode display, or diode laser), (2) devices that detect signals through electronics processes (e.g., photodetectors (e.g., photoconductive cells, photoresistors, photoswitches, phototransistors, phototubes), IR detectors), (3) devices that convert radiation into electrical energy (e.g., a photovoltaic device or solar cell), and (4) devices that include one or more electronic components that include one or more organic semi-conductor layers (e.g., a transistor or diode).

The compounds of the invention are particularly useful as the photoactive material in layer 130, or as an electron transport material in layer 130 or layer 140. In one embodiment, the compounds of the invention are used as the light-emitting material in diodes. In one embodiment, a layer that is greater than 20% by weight new compound, based on the total weight of the layer, up to 100% new compound, can be used as the emitting layer. Additional materials can be present in the emitting layer with the compound of the invention. For example, a fluorescent dye may be present to alter the color of emission. A diluent may also be added and such diluent may be a charge transport material or an inert matrix. A diluent may comprise polymeric materials, small molecule or mixtures thereof. A diluent may act as a processing aid, may improve the physical or electrical properties of films containing the metal compound, may decrease self-quenching in the metal compounds described herein, and/or may decrease the aggregation of the metal compounds described herein. In certain embodiments, the new compound described herein, is present as a guest material in a host material. The term "guest material" is intended to mean a material, within a layer including a host material, that changes the electronic characteristic(s) or the targeted wavelength(s) of radiation emission, reception, or filtering of the layer compared to the electronic characteristic(s) or the wavelength(s) of radiation emission, reception, or filtering of the layer in the absence of such material. The term "host material" is intended to mean a material, usually in the form of a layer, to which a guest material may or may not be added. The host material may or may not have electronic characteristic(s) or the ability to emit, receive, or filter radiation. Non-limiting examples of suitable polymeric host materials include poly(N-vinyl carbazole), conjugated polymers, and polysilane, and mixtures thereof. Non-limiting examples of suitable small molecule host materials include 4,4'-N,N^,-dicarbazole biphenyl (CBP), Bis(2-methyl-8- quinolinolato)(4-phenylphenolato)aluminum (BAIQ) or tertiary aromatic amines and mixtures thereof. Examples of suitable conjugated polymers include polyarylenevinylenes, polyfluorenes, polyoxadiazoles, polyanilines, polythiophenes, polyphenylenes, copolymers thereof and combinations thereof. The conjugated polymer can be a copolymer having non- conjugated portions, for example, acrylic, methacrylic, or vinyl monomeric units. In one embodiment, the diluent comprises homopolymers and copolymers of fluorene and substituted fluorenes. When a diluent is used, the compound of the invention is generally present in a small amount. In one embodiment, the metal compound is less than 20% by weight, based on the total weight of the layer. In one embodiment, the metal compound is less than 10% by weight, based on the total weight of the layer. In some cases the compounds of the invention may be present in more than one isomeric form, or mixtures of different complexes may be present. It will be understood that in the above discussion of OLEDs, the term "compound of the invention" is intended to encompass mixtures of compounds and/or isomers. To achieve a high efficiency LED, the HOMO (highest occupied molecular orbital) of the hole transport material should align with the work function of the anode, the LUMO (lowest un-occupied molecular orbital) of the electron transport material should align with the work function of the cathode. Chemical compatibility and sublimation temp of the materials are also important considerations in selecting the electron and hole transport materials. The other layers in the OLED can be made of any materials which are known to be useful in such layers. The anode 110, is an electrode that is particularly efficient for injecting positive charge carriers. It can be made of, for example materials containing a metal, mixed metal, alloy, metal oxide or mixed-metal oxide, or it can be a conducting polymer. Suitable metals include the Group 11 metals, the metals in Groups 4, 5, and 6, and the Group 8-10 transition metals. If the anode is to be light-transmitting, mixed-metal oxides of Groups 12, 13 and 14 metals, such as indium-tin- oxide, are generally used. The IUPAC numbering system is used throughout, where the groups from the Periodic Table are numbered from left to right as 1-18 (CRC Handbook of Chemistry and Physics, 81^st Edition, 2000). The anode 110 may also comprise an organic material such as polyaniline as described in "Flexible light-emitting diodes made from soluble conducting polymer," Nature vol. 357, pp 477-479 (11 June 1992). At least one of the anode and cathode should be at least partially transparent to allow the generated light to be observed. Examples of hole transport materials for layer 120 have been summarized for example, in Kirk-Othmer Encyclopedia of Chemical Technology, Fourth Edition, Vol. 18, p. 837-860, 1996, by Y. Wang. Both hole transporting molecules and polymers can be used. Commonly used hole transporting molecules are: N,N'-diphenyl-N,N'-bis(3-methylphenyl)- [l (TPD), 4,4'-Bis[N-(1-naphthyl)-N- phenylaminojbiphenyl (NPB, NPD), 1 ,1-bis[(di-4-tolylamino) phenyfjcyclohexane (TAPC), N,N'-bis(4-methylphenyl)-N,N'-bis(4- ethylphenyl)-[1 ,1'-(3,3'-dimethyl)biphenyl]-4,4'-diamine (ETPD), tetrakis-(3- methylphenyl)-N,N,N',N'-2,5-phenylenediamine (PDA), a-phenyl-4-N,N- diphenylaminostyrene (TPS), p-(diethylamino)benzaldehyde diphenylhydrazone (DEH), triphenylamine (TPA), bis[4-(N,N- diethylamino)-2-methylphenyl](4-methylphenyl)methane (MPMP), 1-phenyl-3-[p-(diethylamino)styryl]-5-[p-(diethylamino)phenyl] pyrazoline (PPR or DEASP), 1 ,2-trans-bis(9H-carbazol-9-yl)cyclobutane (DCZB), N,N,N',N'-tetrakis(4-methylphenyl)-(1 ,1'-biphenyl)-4,4'-diamine (TTB), and porphyrinic compounds, such as copper phthalocyanine. Commonly used hole transporting polymers are polyvinylcarbazole, (phenylmethyl)polysilane, and polyaniline. It is also possible to obtain hole transporting polymers by doping hole transporting molecules such as those mentioned above into polymers such as polystyrene and polycarbonate. Examples of other electron transport materials for layer 140 include metal chelated oxinoid compounds, such as tris(8-hydroxyquinolato)aluminum (Alq₃); phenanthroline-based compounds, such as 2,9-dimethyl-4,7-diphenyl-1 ,10-phenanthroline (DDPA) or 4,7-diphenyl-1 ,10-phenanthroline (DPA), and azole compounds such as 2-(4-biphenylyl)-5-(4-t-butylphenyl)-1 ,3,4-oxadiazole (PBD) and 3-(4-biphenylyl)-4-phenyl-5-(4-t-butylphenyl)-1 ,2,4-triazole (TAZ). Layer 140 can function both to facilitate electron transport, and also serve as a buffer layer or confinement layer to prevent quenching of the exciton at layer interfaces. Preferably, this layer promotes electron mobility and reduces exciton quenching. The cathode 150, is an electrode that is particularly efficient for injecting electrons or negative charge carriers. The cathode can be any metal or nonmetal having a lower work function than the anode. Materials for the cathode can be selected from alkali metals of Group 1 (e.g., Li, Cs), the Group 2 (alkaline earth) metals, the Group 12 metals, including the rare earth elements and lanthanides, and the actinides. Materials such as aluminum, indium, calcium, barium, samarium and magnesium, as well as combinations, can be used. Li-containing organometallic compounds can also be deposited between the organic layer and the cathode layer to lower the operating voltage. It is known to have other layers in organic electronic devices. For example, there can be additional layers (not shown) between the anode layer 110 and the active layer 130 to facilitate positive charge transport and/or band-gap matching of the layers, or to function as a protective layer. Similarly, there can be additional layers (not shown) between the active layer 130 and the cathode layer 150 to facilitate negative charge transport and/or band-gap matching between the layers, or to function as a protective layer. Layers that are known in the art can be used. In addition, any of the above-described layers can be made of two or more layers. Alternatively, some or all of inorganic anode layer 110, the hole transporting layer 120, the active layer 130, and cathode layer 150, may be surface treated to increase charge carrier transport efficiency. The choice of materials for each of the component layers is preferably determined by balancing the goals of providing a device with high device efficiency. It is understood that each functional layer may be made up of more than one layer. The device can be prepared by sequentially vapor depositing the individual layers on a suitable substrate. Substrates such as glass and polymeric films can be used. Conventional vapor deposition techniques can be used, such as thermal evaporation, chemical vapor deposition, and the like. Alternatively, the organic layers can be coated from solutions or dispersions in suitable solvents, using any conventional coating technique. In general, the different layers will have the following range of thicknesses: anode 110, 500-5000A, preferably 1000-2000A; hole transport layer 120, 50-1000A, preferably 200-800A; light-emitting layer 130, 10-1000 A, preferably 100-800A; electron transport layer 140, 50-1 OOOA, preferably 200-800A; cathode 150, 200-1 OOOOA, preferably 300-5000A. The location of the electron-hole recombination zone in the device, and thus the emission spectrum of the device, can be affected by the relative thickness of each layer. Thus the thickness of the electron-transport layer should be chosen so that the electron-hole recombination zone is in the light-emitting layer. The desired ratio of layer thicknesses will depend on the exact nature of the materials used. It is understood that the efficiency of devices made with the compounds of the invention, can be further improved by optimizing the other layers in the device. For example, more efficient cathodes such as Ca, Ba or LiF can be used. Shaped substrates and novel hole transport materials that result in a reduction in operating voltage or increase quantum efficiency are also applicable. Additional layers can also be added to tailor the energy levels of the various layers and facilitate electroluminescence. The compounds of the invention often are phosphorescent and photoluminescent and may be useful in applications other than OLEDs. For example, phosphorescent organometallic compounds have been used as oxygen sensitive indicators, as phosphorescent indicators in bioassays, and as catalysts. As used herein, the term "compound" is intended to mean an electrically uncharged substance made up of molecules that further consist of atoms, wherein the atoms cannot be separated by physical means. The term "ligand" is intended to mean a molecule, ion, or atom that is attached to the coordination sphere of a metallic ion. The term "complex", when used as a noun, is intended to mean a compound having at least one metallic ion and at least one ligand. The term "monodentate ligand" refers to a ligand that occupies one coordination site in the coordination sphere of a metallic ion. Analogously, the terms "bidentate ligand" and "tridentate ligand" refer to ligands that occupy two and three coordination sites, respectively, in the coordination sphere of a metallic ion. The term "group" is intended to mean a part of a compound, such a substituent in an organic compound or a ligand in a complex. The term "hexacoordinate" is intended to mean that six groups or points of attachment are coordinated to a central metal. The term "tetracoordinate" is intended to mean that four groups or points of attachment are coordinated to a central metal. The phrase "adjacent to," when used to refer to layers in a device, does not necessarily mean that one layer is immediately next to another layer. On the other hand, the phrase "adjacent R groups," is used to refer to R groups that are next to each other in a chemical formula (i.e., R groups that are on atoms joined by a bond). The term "photoactive" is intended to mean any material that exhibits electroluminescence or photosensitivity. The term "active" or "electrically active", when referring to a layer or material, is intended to mean a layer or material that exhibits electronic or electro-radiative properties. An active layer material may emit radiation or exhibit a change in concentration of electron-hole pairs when receiving radiation. In the Formulae, the letters L, M, Q, R, Y, Z, and Fw are used to designate atoms or groups which are defined within. All other letters are used to designate conventional atomic symbols.

As used herein, "liquid or solution processing or solution deposition" refers to the formation of uniform films from a liquid medium. In one embodiment, the film is robust. The deposition techniques include any continuous or discontinuous method of depositing a material that is in the form of a liquid medium. The term "layer" is used interchangeably with the term "film" and refers toa coating covering a desired area. The term is not limited by size. For example, in some embodiments, the area can be as large as an entire device. In other embodiments, the area can be as small as a specific functional area such as the actual visual display, or as small as a single sub-pixel. In addition, the area can be continuous or discontinuous. Layers can be formed by any conventional deposition technique, including, but not limited to, vapor deposition, liquid deposition, and thermal transfer. For, example, in some embodiments, the layer may be made by] spin coating, gravure coating, curtain coating, dip coating, slot- die coating, spray coating, continuous nozzle coating, and discontinuous deposition techniques such as ink jet printing, contact printing such as gravure printing, screen printing, and the like, or indeed, any other way which is effective in causing a layer to come into existence.

As used herein, the term "alkyl" is intended to mean a group derived from an aliphatic hydrocarbon having one point of attachment, which group may be linear, branched or cyclic. The term "alkylene" is intended to mean a group derived from an alkyl group and having two or more points of attachment. As used herein, the term "alkenyl" is intended to mean a group derived from a hydrocarbon having one or more carbon-carbon double bonds and having one point of attachment, which group may be linear, branched or cyclic. The term "alkenylene" is intended to mean a group derived from an alkenyl group and having one or more carbon-carbon double bonds and having two or more points of attachment. As used herein, the term "alkynyl" is intended to mean a group derived from a hydrocarbon having one or more carbon-carbon triple bonds and having one point of attachment, which group may be linear, branched or cyclic. The term "alkynylene" is intended to mean a group derived from an alkynyl group and having two or more points of attachment. As used herein, the term "aryl" is intended to mean a group derived from an aromatic hydrocarbon having one point of attachment. The term "arylene" is intended to mean a group derived from an aryl group and having two points of attachment. As used herein, the term "arylalkylene" is intended to mean a group derived from an alkyl group having an aryl substituent. As used herein, the term "arylenealkylene" is intended to mean a group having both aryl and alkyl groups and having one point of attachment on an aryl group and one point of attachment on an alkyl group. As used herein, "hydrocarbyl" refers to a moiety that is composed primarily of carbon and hydrogen atoms. As used herein, a "hydrocarbyl" moiety may also contain heteroatoms, e.g., N, O, P, and the like. As used herein, "inorganic" refers to a moiety that is composed primarily of atoms other than carbon. As used herein, the term "solvent-solubilizing" indicates that the solubility or dispersability of a material in at least one organic solvent has been increased. As used herein, the prefix "fluoro" is intended to mean that one or more hydrogens has been replace by fluorine, including completely hydrogenated, partially fluorinated and perfluorinated substituents. As used herein, the prefix "hetero" indicates that at least one of the carbon atoms forming the group has been replaced by a heteroatom. Such heteroatoms include, e.g., N, O, P, and the like, see page 16 Unless otherwise indicated, all groups can be unsubstituted or substituted. As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present). Also, use of the "a" or "an" are employed to describe elements and components of the invention. This is done merely for convenience and to give a general sense of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting. It is to be appreciated that certain features of the invention which are, for clarity, described above and below in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any subcombination. Further, reference to values stated in ranges include each and every value within that range.

EXAMPLES The following examples illustrate certain features and advantages of the present invention. They are intended to be illustrative of the invention, but not limiting. All percentages are by weight, unless otherwise indicated. EXAMPLE 1 This example illustrates the preparation of a new organometallic compound having Formula I, where d = 4, compound 1.

compound 1

An aryl framework structure with acetylacetonate (acac) as ligands (Y) was prepared as follows. Inside a N2~filled glove box, a 100 cc glass pot, equipped with a dropping funnel, rubber-covered stoppers and stir bar, was charged with 3.20 g(32 equiv.) of 2,4-pentanedione and 35 cc THF. A glass bottle, with a septum seal, was charged with 1.83 g (4.17 equiv.) of 1 ,2,4,5-tetra-bromomethylbenzene and 25 cc THF. A glass syringe, equipped with a valve, was charged with 35 cc of 2 M (70 equiv.) of LDA (lithium diisopropylamide) in ethylbenzene/THF/heptane solution. The pot, bottle and syringe were transferred to a fume hood where the pot was clamped in place and a N2 purge was placed on top of the dropping funnel. A dry ice-acetone cooling bath was used to cool the pot and stirring was started. After 15 min., low N2 pressure was used with a cannula to transfer the solution from the bottle to the pot. The solution in the syringe was injected into the pot over about 15 min. with stirring. Stirring with dry ice-acetone cooling was continued for 1 hr. The solution in the dropping funnel was added to the pot, over a period of 10-15 min, with stirring and dry ice-acetone cooling, and continued for an additional hr. Cooling was changed to wet ice and stirring was continued for 3 hr. The wet ice was allowed to slowly melt over night, while stirring was continued. A quench solution was prepared from 45 cc of ice water and 15 cc of concentrated HCI. The pot contents were slowly poured into the quench solution, followed by shaking of the resulting mixture in a separatory funnel. The reaction mixture was extracted three times with -50 cc portions of methylene chloride, dried over MgSO4 and was vacuum stripped to give 2.67 g of crude product. A 1.03 g portion of crude product was purified by elution from a 2 cm diam. x 4 cm column of silica gel, using successively: methylene chloride, methylene chloride/ethyl acetate (50/50), ethyl acetate, and finally methanol. Upon evaporation of solvent, methylene chloride afforded 0.062g of final product and the methylene chloride/ ethyl acetate fraction eluted 0.233g of final product. The combined yield of 0.295g of final product was 28%, based on starting 1 ,2,4,5-tetra-bromomethylbenzene. ¹ H NMR (CD₂Cl₂, 20°C), δ: 6.8(4H), 5.4(1 H), 3.5(2H), 2.8(2H), 2.5(2H), 2.1 (3H), and 1.9(3H). The aryl framework structure with ligands (L⁴) attached was complexed to an organometallic Ir compound (already having 2 ligands (L¹) coordinated thereto) as follows. A mixture of 0.11g (-0.21 equiv.) of 1 ,2,4,5-tetra-(3,5-dioxo-hexyl)benzene (as prepared above) , 0.21 g (0.87 equiv.) of NaH and 25 cc of 1 ,2-dimethoxyethane was stirred under N . After 10 min., 0.594g (0.42 equiv.) of bis-2-(4-fluorophenyl)-5- trifluoromethylpyridine-iridium-chloride bridged dimer, made according to the procedure in published PCT application WO 02/02714, was added and was stirred at 85°C (oil bath) overnight. Next, 0.1 Og ( 0.72 equiv.) of K₂CO₃ and 0.050 cc H₂O were added to the mixture. Stirring and heating at 85°C were continued over night. The resulting mixture of a clear orange solution and light yellow solids was filtered and the filtrate was evaporated to afford 0.59g of orange solids. A 0.142g sample of orange solids was purified by elution from a 2 cm diam. x 7 cm column of silica gel, using methylene chloride followed by methylene chloride/ methanol (50/50). Early fractions of methylene chloride eluent were evaporated to afford 0.075g of yellow solid. The overall yield of tetra-lr- substituted compound was 46%, based on starting 1 ,2,4,5-tetra-(3,5- dioxo-hexyl)benzene (compound E103291 -125). ¹H NMR (CD₂CI₂, 20°C), 1H NMR (CD₂CI₂, 20°C), δ: 8.6(2H), 7.9(2H), 7.75(2H), 7.6(2H), 7.45(4H), 6.6(2H), 6.45(1 H), 5.85(2H), 2.3(2H), 2.0(2H), and 1.7(3H). 1⁹F NMR (CD₂CI₂, 20°C), 109.3(1 F), 63.2(3F) and 63.0(3F). EXAMPLE 2 This example illustrates the preparation of a new organometallic compound having Formula I, where e = f = 0, compound 2.

compound 2

As the facial isomer, where three nitrogens are all adjacent, i.e. at the corners of one face of the octahedron around the lr.2-(3- bromophenyl)-pyridine was prepared using standard Suzuki coupling conditions via condensation of 2-bromopyridine with 3- bromophenylboronic acid in ethylene glycoldimethylether in the presence of a palladium tetrakis-triphenylphosphine catalyst. Isolated yield after distillation was 40%. A second Suzuki coupling of this first material with 3- trifluoromethylphenylboronic acid also using a palladium phosphine catalyst gave the desired L¹ ligand in 98% yield. 0.9g of the above phenylpyridine compound and 0.38g iridium chloride were mixed with 0.75g silver trifluoroacetate in 2mL 2- ethoxyethanol and 0.5mL water. The mixture was stirred and refluxed under nitrogen for 4hr then cooled to room temperature. The solution was evaporated to dryness by gentle heating in a nitrogen stream and the resulting solid was extracted into methylene chloride (large volume) and filtered to remove dark solids containing silver. The residue was washed with additional methylene chloride until no further yellow color eluted. The bright yellow solution was evaporated to dryness and checked by TLC. The yellow solid was purified by chromatography on silica gel using toluene as eluent and the fastest running yellow band was collected. The recovered yellow solution was evaporated and recrystallized from methanol/methylene chloride 1 :1. NMR of the yellow crystals in methylene chloride showed the expected spectrum for the desired material as the fac isomer(¹⁹F singlet at -63.25ppm). The recovered solid was quite soluble in toluene, methylene chloride, ethyl acetate etc. Yield 35%. EXAMPLE 3 This example illustrates new organometallic compounds having Formula I where e = f = 0, compound 3.

compound 3 as the fac isomer.

Compound 3a, R = 4-F This was prepared in an identical manner to that described for compound 2 above substituting 4-fluorophenyl boronic acid for 3- trifluoromethylboronic acid in the ligand synthesis. NMR of final product showed it to be the desired compound as the fac isomer(¹⁹F triplet of triplets at -118.65ppm) Compound 3b, R = 4-n-butyl This was prepared in an identical manner to that described for compound 2 above substituting 4-n-butyl-phenyl boronic acid for 3- trifluoromethylboronic acid in the ligand synthesis. NMR of final product showed it to be the desired compound as the fac isomer(¹H : δ: 7.9(1 H) d; 7.8(1 H) d; 7.55 (1 H) t; 7.52 (1 H)d; 7.42 (2H) d; 7.11 (2H)d; 7.0 (1 H)d; 6.85 (2H)m; 2.52 (2H)m; 1.50(2H)m; 1.25 (2H)m; 0.90 (3H) t.) Compound 3c, R = 4-t-butyl This was prepared in an identical manner to that described for compound 2 above substituting 4-t-butyl-phenyl boronic acid for 3- trifluoromethylboronic acid in the ligand synthesis. NMR of final product showed it to be the desired compound as the fac isomer(¹ H δ: 7.9(1 H) d; 7.78(1 H) d; 7.55 (1 H) t; 7.50 (1 H)d; 7.40 (2H) d; 7.23 (2H)d; 6.93 (1 H)d; 6.80 (2H)m; 1.19 (9H) s.) Compound 3d, R = 3.5-CF3 This was prepared in an identical manner to that described for compound 2 above substituting 3,5-bis-trifluoromethylphenyl boronic acid for 3-trifluoromethylboronic acid in the ligand synthesis. NMR of final product showed it to be the desired compound as the fac isomer(¹⁹F singlet at -63.56ppm). EXAMPLE 4 This example illustrates the preparation of a new organometallic compound having Formula I where e = f = 0, compound 4.

compound 4

where r is 1 or 2. 1.0 g of the phenylpyridine ligand 2-(3-phenyl)-phenylpyridine (prepared as in example 2 above except substituting phenylboronic acid for 3-trifluoromethylboronic acid) was mixed with 0.76g iridium chloride in 10mL 2-ethoxyethanol and 1 mL water. This mixture was refluxed under nitrogen for 30mins then cooled to room tmeperature and evaporated to dryness in a nitrogen stream. The yellow solid was extracted into methylene chloride and filtered. The resulting yellow solution was evaporated to dryness to isolate chloro dimer in 85% yield. The chlorodimer (0.69 g) was mixed with 2 eq (0.58 g) of the ligand 2-(3-(4-t-butylphenyl))-phenylpyridine prepared in example 3c above and 1q silver trifluoroacetate in 2-ethoxyethanol. The mixture was refluxed for 2 hrs then evaporated to dryness and extracted into methylene chloride. Chromatography on silica using methylene chloride as eluent produced a fast running green luminescent band. Collection of this band, evaporation and recrystallization from methylene chloride/methanol gave a bright yellow powdery solid. NMR in methylene chloride showed it to be a mixture of fac isomers of 2 materials of the structure shown where r=1 (compound 4a) and r=2 (compound 4b) in an approximate ratio of 1 :10. EXAMPLE 5 This example illustrates the preparation of an intermediate framework-ligand, compound 5.

An anhydrous THF (10 mL) solution of methyl tert-butyl ketone (0.907 g, 9.08 mmol) was added dropwise to a refluxing mixture of NaH (0.218 g, 9.08 mmol), dimethyl-1 ,4- cubanedicarboxylate in 50 mL of anhydrousTHF and then was allowed to reflux for 16 h. The orange mixture was cooled to room temperature and poured over stirring ice/water, followed by extraction with ethyl ether (2x100 mL). The aqueous layer was acidified, resulting in a white precipitate. The solids where extracted with ether, washed with water, brine and dried over magnesium sulfate. The dry ether solution was evaporated under vacuum to give compound 5 as a tan solid in 46% yield (740 mg). EXAMPLE 6 This example illustrates the preparation of a new organometallic compound having Formula I, where d= 2, compound 6.

Under an inert atmosphere of nitrogen, a mixture of acetylacetonate ligand from example 5 (0.120 g, 0.34 mmol) and [lrOH{1-(4-tert-butyl-phenyl)-isoquinoline}₂]₂ (0.500 g, 0.340 mmol) in 25 mL anhydrousTHF was refluxed for 3 days. The volatiles were removed by evaporation to a give dark residue. This residue was washed in hexanes to give a dark red powder, which was further purified by flash chromatography (silica, ethyl acetate) to yield the desired product (0.213 g, 35% yield). EXAMPLE 7 This example illustrates the formation of a new organometallic compound having Formula I, where d = 2, compound 7.

The procedure outlined in example 6 was used starting [lrOH{2-(4- fluoro-phenyl)-(5-trifluoromethyl)pyridine}₂]₂ (0.500 g, 0.353 mmol) and acetyacetonate ligand from example 1 (0.126 g, 0.353 mmol). The desired iridium compound was isolated as a yellow powder (0.107 g, 17.5% yield) after purification using flash chromatography (silica, CH₂CI₂). ¹⁹F NMR (CD₂CI₂) D: -63.13 (F), -109.9 (CF₃). EXAMPLE 8 This example illustrates the preparation of a precursor framework- ligand, compound 8.

To a cooled (-78 C) THF (35 mL) solution of 2,4-pentanedione (2.13 mL, 20.82 mmol) under nitrogen, 2.0M lithium diisopropylamide (20.8 ml, 41.6 mmol) was slowly added. This mixture was allowed to stir at -78C for one hour, after which a THF (25mL) solution of dibromo-p- xylene (2.199 g, 8.33 mmol ). The reaction was kept at -78C for 30 min. and the slowly warmed up to room temperature. The mixture was quenched with 4M HCI, extracted with Et₂O and dried over sodium sulfate. The product was purified by distillation and using flash chromatography to give the product as an oil in 32% yield (0.8 grams). Example 9 This example illustrates the preparation of a new organometallic compound having Formula I, where d = 2, compound 9.

The procedure for example 6 was employed with [lrOH{1-(4-tert- butyl-phenyl)-isoquinoline}₂]₂ (0.483 g, 0.33 mmol) and acetylacetonate ligand from example 8 (0.100 g, 0.33 mmol). The crude product was purified crystallization from CH₂CI₂/hexane to give the product as a dark red solid (0.125 g, 22 % yield). EXAMPLE 10 This example illustrates the preparation of a new organometallic compound having Formula I, where d = 2, compound 10.

The procedure for example 6 was employed with with [lrOH{2-(4- fluoro-phenyl)-(5-trifluoromethyl)pyridine}₂]₂ (0.456 g, 0.33 mmol) and acetylacetonate ligand from example 8 (0.100 g, 0.33 mmol). The crude product was purified by chromatography (CH₂CI₂) to give the product as a yellow powder (0.270 g, 50 % yield). ⁹F NMR (CD₂CI₂, 376.8 MHz) δ - 63.04 (CF₃), -63.22 (CF₃), 109.45 (F). EXAMPLE 11 This example illustrates the preparation of a new organometallic compound having Formula I, where e = f = 0, compound 11.

Under an atmosphere of nitrogen, an ethoxyethanol (50 mL) solution of {lrCI[4-t-Bu-phenyl)-isoquinoline]2}2 (synthesized following procedure outlined in WO-0340256, 3.00 g, 2. 01 mmol) and Na(5-ethyl- nonane-2,4-dione) (synthesized by reacting NaH with 5-ethyl-nonane-2,4- dione (GB 615523) 0.867 g, 4.21 mmol) were stirred at 120 C for 45 min. The mixture was evaporated to dryness and the residue was dissolved in CH₂CI₂ and passed through a pad of silica with CH₂CI₂ as the eluting solvent. The crude product was isolated by evaporation and then was further purified using chromatography (silica, CH₂CI₂) to give the product is 54% yield (1.95 g). ¹H NMR (CD₂CI₂, 500 MHz) δ 0.44 (3H), 0.58 (3H), 0.92 (9H), 1.03 (9H), 1.03-1.25 (12H), 5.25 (1 H), 6.16 (1 H), 6.52 (1 H), 7.03 (2H), 7.50 (2H), 7.73 (4H), 7.93 (2H), 8.12 (2H), 8.47 (2H), 8.94 (2H). EXAMPLE 12 This example illustrates the preparation of a new organometallic compound having Formula I, where e = f = 0. compound 12.

The procedure for example 11 was employed using {lrCI[2- pheny!quinoline]2}2 (synthesized following procedure outlined in WO- 0340256, 2.25 g, 3.5 mmol) and Na(5-ethyl-nonane-2,4-dione) (synthesized by reacting NaH with 5-ethyl-nonane-2,4-dione (GB 615523) 1.08 g, 5.25 mmol). Compound 12 was isolated as a bright-red crystalline solid in 68% yield (1.86 g).

EXAMPLE 13 This example illustrates the preparation of a new organometallic compound having Formula I, where d = 2, compound 13.

The procedure for example 6 was employed with [lrOH{2-(4-fluoro- phenyl)-(5-trifluoromethyl)pyridine}₂]₂ (0.250 g, 0.171 mmol) and acetylacetonate ligand A (synthesized following procedure outlined in example 8, 0.065 g, 0.171 mmol). The crude product was purified by flash chromatography, using methylene chloride/hexanes (9:1 ), to yield the desired product as a red powder in 30.5% yield (0.094 g). EXAMPLE 14 This example illustrates the preparation of a new organometallic compound having Formula I, where d = 2, compound 14. The procedure outlined in example 6 was used starting with

[lrOH{2-(4-fluoro-phenyl)-(5-trifluoromethyl)pyridine}₂]₂ (0.250 g, 0.177 mmol) and acetyacetonate ligand A (synthesized following procedure outlined in example 8, 0.067 g, 0.177 mmol). The desired iridium compound was isolated as a yellow-orange powder (0.100 g, 32 % yield) by crystallization from CH₂CI₂/hexane. ¹⁹F NMR (CD₂Cl₂, 376.8 MHz) δ - 63.04, -63.08, - 63.18, - 63.19, 109.45. Anal. Calcd: C, 49.18; H, 2.76; N, 3.17. Found: C, 50.17; H, 2.86; N, 3.49. EXAMPLE 15 This example illustrates the preparation of a new organometallic compound having Formula I, where d = 2, compound 15.

The procedure outlined in example 6 was used starting [lrOH{2-(4- fluoro-phenyl)-(5-trifluoromethyl)pyridine}₂]2 (0.250 g, 0.177 mmol) and acetyacetonate ligand C (synthesized following procedure outlined in example 8, 0.074 g, 0.177 mmol). The desired iridium compound was isolated as a yellow-orange powder (0.214 g, 67% yield) by crystallization from CH₂Cl₂/hexane. 1⁹F NMR (CD₂CI₂, 376.8 MHz) δ - 63.1 , 109.44. Anal. Calcd: C, 50.03; H, 3.03; N, 3.11. Found: C, 50.27; H, 2.88; N, 3.00. EXAMPLE 16 This example illustrates the fabrication of an organic light emitting diode (OLED) using a polymetallic red-emissive material (compound 9 from example 9, illustrated below) as a dopant in a poly(fluorene) matrix. The resulting blend is used as the active red-emissive layer in an OLED. The electrical performance of this device is compared to an identical OLED, except that the second device contains the analogous monometallic compound (compound 11 from example 11 , illustrated below) as the red dopant instead of the polymetallic compound.

compound 11 compound 9 Monometallic Compound Polymetallic compound OLED with a Polymetallic Red-Emissive Compound. The organic film components in this OLED example were all solution processed. Device assembly is as follows: ITO/glass substrate (Applied Films) was patterned (device active area = entire 25 mm²) and cleaned ultrasonically using aqueous detergent followed by isopropanol. The substrate was then further cleaned by placing in a 300 W oxygen plasma oven for 15 min. A poly(ethylenedioxythiophene)- poly(styrenesufonic acid) (PEDOT-PSSA, Bayer Corp.) buffer layer (i.e. hole transport injection layer) was then spin-coated to a thickness of 60 nm. The film was dried on a hotplate at 200 °C for 3 min. The substrate was then transferred to a nitrogen-filled glovebox, at which point a solution of poly(fluorene) (75 mg), the red-emissive polymetallic compound (1.5 mg), and anhydrous toluene (7.5 mL) were spin coated on the substrate to a thickness of 70 nm. The substrate was then transferred to a high vacuum chamber, where LiF (2.0 nm) followed by Ca (20.0 nm) and then Al (400 nm) were thermally deposited at 2.0 x 10^-6 torr. The resulting OLED device was then sealed from air by gluing a glass slide on top of the cathode with the use of a UV-curable epoxy resin. The device was fully characterized by acquiring current-voltage, luminance-voltage, luminance-current, efficiency-voltage, and efficiency- current profiles. This was accomplished with the use of a computer-driven (Labview software) Keithley Source-Measurement Unit and a photodiode, the latter which integrated light output over the entire 25 mm² device active area. An electroluminescence spectrum was also acquired, showing the light output from this OLED to have color coordinates u' = 0.49, v' = 0.52. Average performance from seven separate devices is as follows: turn-on (at 10 cd/m²) = 5.0 V; operating voltage (at 200 cd/m²) = 5.9 V; efficiency = 2.0 cd/A at 200 cd/m². OLED with the Analogous Monometallic Red-Emissive Compound. The organic film components in this OLED example were all solution processed. Device assembly was as follows: ITO/glass substrate (Applied Films) was patterned (device active area = entire 25 mm²) and cleaned ultrasonically using aqueous detergent followed by isopropanol. The substrate was then further cleaned by placing in a 300 W oxygen plasma oven for 15 min. A poly(ethylenedioxythiophene)-poly(styrenesufonic acid) (PEDOT-PSSA, Bayer Corp.) buffer layer (i.e. hole transport/injection layer) was then spin-coated to a thickness of 60 nm. The film was dried on a hotplate at 200 °C for 3 min. The substrate was then transferred to a nitrogen-filled glovebox, at which point a solution of poly(fluorene) (75 mg), the red-emissive monometallic compound (1.5 mg), and anhydrous toluene (7.5 mL) were spin coated on the substrate to a thickness of 70 nm. The substrate was then transferred to a high vacuum chamber, where LiF (2.0 nm) followed by Ca (20.0 nm) and then Al (400 nm) were thermally deposited at 2.0 x 10"⁶ torr. The resulting OLED device was then sealed from air by gluing a glass slide on top of the cathode with the use of a UV-curable epoxy resin. The device was fully characterized by acquiring current-voltage, luminance-voltage, luminance-current, efficiency-voltage, and efficiency- current profiles. This was accomplished with the use of a computer-driven (Labview software) Keithley Source-Measurement Unit and a photodiode, the latter which integrated light output over the entire 25 mm² device active area. An electroluminescence spectrum was also acquired, showing the light output from this OLED to have color coordinates u' = 0.49, v' =

0.52. Average performance from seven separate devices is as follows: turn-on (at 10 cd/m²) = 4.6 V; operating voltage (at 200 cd/m²) = 5.3 V; efficiency = 1.9 cd/A at 200 cd/m². EXAMPLE 17 This example illustrates the preparation of a new organometallic compound having Formula I, where e = f = 0, and a = 3, compound 17.

A suspension of iridium(lll) fr/s(2-(5'-bromophenyl)pyridinato-/V,C^2') (0.250 g, 0.28 mmol), 4-(n-butoxyphenyl)boronic acid (0.181 g, 0.93 mmol), a 2M solution of potassium carbonate (20.5 mL) and Pd(PPh3)4 (0.024 g, 0.021 mmol) in THF (34 mL), toluene (27 mL) and ethanol (10 mL) was placed under nitrogen and heated at reflux for 24 h. The mixture was diluted CH2CI2 (25mL) and water (25 mL) and the yellow organic layer was separated and washed twice with water, dried with magnesium sulfate, filtered and taken to dryness. The crude material was passed through a short silica column with 75% CH2Cl2/hexane, concentrated and dried in vacuo to afford compound 17 (85 mg, 27 %) as a yellow powder. EXAMPLE 18 This example illustrates the preparation of a new organometallic compound having Formula I, where e = f = 0, and a = 2, compound 18.

[correct no. to 18].

The procedure used for the synthesis of compound 178 was employed, using iridium(lll) fr/s(2-(5^'-bromophenyl)pyridinato-Λ/,C^2') (0.015 g, 0.016 mmol), 3,5-di(2-ethylhexyloxy)phenylboronic acid (0.029 g, 0.054 mmol), a 2M solution of potassium carbonate (0.6 mL) and Pd(PPh3)4 (0.126 g, 0.011 mmol). Compound 18 was isolated as a colorless oil in 89% yield (31 mg).

Claims

CLAIMS What is claimed is: 1 . An organic electronic device comprising at least one layer comprising a compound having a formula selected from Formula I, Formula II, or Formula HI

L¹ _aL² _bL³ _cM L⁴_Y_e - - (FW)_f (I)

wherein: L¹ is selected from an aryl-N-heterocycle ligand and a heteroaryl-N-heterocycle ligand L² is an anionic ligand L³ is a nonionic ligand L⁴ is selected from L¹ and L² M is a metal selected from Re, Ru, Os, Rh, Ir, Pd, Pt, and Au FW is a moiety capable of bearing at least two (L⁴ -Y_e) groups Y is a group selected from alkylene, heteroalkylene, alkenylene, heteroalkenylene, and alkynylene a is selected from 1 and 2 b is selected from 0 and 1 c is selected from 0, 1 , and 2 d is selected from an integer from 1 through 8 e is selected from 0 and 1 f is selected from 0 and 1 g is selected from an integer from 1 through 4, and h is selected from l and 2, with the proviso that a, b, and c are selected such that the metal is tetracoordinate when M is Au, Pd, or Pt, and the metal is hexacoordinate when M is Re, Ru, Os, Rh, or Ir, and with the proviso that when f = 0, then e = 0 and there is at least one substituent R¹ on at least one ligand, wherein R is solvent- solubilizing.

2. The device of Claim 1 , wherein M is selected from Os, Ir, and Pt.

3. The device of Claim 1 , wherein L¹ is selected from a phenylpyridine, phenyl-pyrimidine, phenyl-quinoline, bipyridine, and thienyl- pyridine.

4. The device of Claim 1 having Formula I, wherein a = 2, b = 0, c = 0, and L⁴ is a bidentate monoanionic ligand.

5. The device of Claim 4, wherein L⁴ is selected from β-enolate ligands, N analogs of ?-enolate ligands, S analogs of -enolate ligands; aminocarboxylate ligands; iminocarboxylate ligands; salicylate ligands; hydroxyquinolinate ligands; S analogs of hydroxyquinolinate ligands; and phosphinoalkoxide ligands.

6. The device of Claim 1 , wherein there is at least one R¹ substituent on an aryl or heteroaryl ring, and R¹ is selected from alkyl, fluoroalkyl, aryl, fluoroaryl, alkylaryl, alkoxy, aryloxy, fluoroalkoxy, fluoraryloxy, heteroalkyl, fluoroheteroalkyl, heteroaryl, fluoroheteroaryl, heteroalkylaryl, heteroalkoxy, heteroaryloxy, fluoroheteroalkoxy, and fluorheteroaryloxy.

7. The device of Claim 1 having Formula I, wherein e = 0, f = 0, and R¹ is selected from alkyl, fluoroalkyl, aryl, fluoroaryl, alkylaryl, alkoxy, aryloxy, fluoroalkoxy, fluoraryloxy, heteroalkyl, fluoroheteroalkyl, heteroaryl, fluoroheteroaryl, heteroalkylaryl, heteroalkoxy, heteroaryloxy, fluoroheteroalkoxy, and fluoroheteroaryloxy.

8. The device of Claim 7, wherein R¹ is selected from phenyl, fluorophenyl, alkylphenyl, fluoroalkylphenyl, alkoxy phenyl, and fluoroalkoxyphenyl.

9. The device of Claim 7, wherein a = 2, b = 0, c = 0, and L⁴ = L¹.

10. The device of Claim 7, wherein a = 2, b = 0, c = 0, and L⁴ is selected from ?-enolate ligands, N analogs of ?-enolate ligands, S analogs of ?-enolate ligands; aminocarboxylate ligands; iminocarboxylate ligands; salicylate ligands; hydroxyquinolinate ligands; S analogs of hydroxyquinolinate ligands; and phosphinoalkoxide ligands.

11. The device of Claim 1 wherein the at least one layer is a light- emitting layer.

12. The device of Claim 11 wherein the light-emitting layer further comprises a diluent.

13. The device of Claim 12 wherein the diluent comprises a polymeric or small molecule material, or a mixture thereof.

14. A compound selected from

15. A compound selected from

where R^a = 3-CF₃, 4-F, 4- n-butyl, 4-f-butyl, A-n- butoxy, 3,5-CF₃,

where R^a = 3-CF₃, 4-F, 4- where R^b = H, 3-CF₃, 4-F, /7-butyl, 4-f-butyl, 4-n- 4-n-butyl, 4-t-butyl, A-n- butoxy, 3,5-CF₃, butoxy, 3,5-CF₃, and r = 1 or 2

43 where: R^c through R⁹ are the same or different and are selected from H and R¹, with at least one of R^c through R^g selected from phenyl, fluorophenyl, and heteroaryl R^h is the same or different at each occurrence and is selected from F, alkyl, aryl, fluoroalkyl, and alkoxy

remove formula 2 above.

16. A compound selected from

Compound 1

compound 2

compound 3 as the fac isomer.

compound 4

compound 6

compound 7

compound 9

compound 10

15 compound 11

compound 12

compound 13

compound 14

compound 15

compound 17

compound 18

17. An organic electronic device comprising at least one layer comprising the compound of Claim 14.

18. An organic electronic device comprising at least one layer comprising the compound of Claim 15.

19. An organic electronic device comprising at least one layer comprising the compound of Claim 16.

20. A composition comprising at least one of the compounds of Claim 1.

21. The composition of Claim 20 further comprising a host.

22. The composition of Claim 21 , wherein the host is selected from poly(N-vinyl carbazole), conjugated polymers, polysilane, tertiary aromatic amines, and mixtures thereof.

23. The composition of Claim 20 wherein the host is selected from polyarylenevinylenes, polyfluorenes, polyoxadiazoles, polyanilines, polythiophenes, polyphenylenes, copolymers thereof, and mixtures thereof.