GB2254610A

GB2254610A - Preparation of small protic lewis base complexes of metal salts of organic acids

Info

Publication number: GB2254610A
Application number: GB9106834A
Authority: GB
Inventors: Ronald Snaith; Dominic Simon Wright; Matthew Gwilym Davidson
Original assignee: Associated Octel Co Ltd
Current assignee: Innospec Ltd
Priority date: 1991-04-02
Filing date: 1991-04-02
Publication date: 1992-10-14
Anticipated expiration: 2011-04-02
Also published as: GB9106834D0; GB2254610B

Abstract

Metallic salt coordination complexes of a metal M and an acid organic compound RH and which contain a small protic donor base ligand, e.g. H2O, NH3, H2S, H2Se or CH3OH, and optically an organic donor ligand (L), are obtained by reacting under anhydrous conditions a compound, e.g. a hydroxide, of the metal M and the protic donor ligand with the organic compound RH, the reaction being carried out in an anhydrous aromatic solvent optionally containing the donor ligand (L). The complex, e.g. RM.H2O.L, precipitates on cooling.

Description

METHOD FOR THE rzEr PREPARATION OF AQUAND~OTHER SMALL PROTIC LEWIS BASE COMPLEXES OF METAL SALTS OF ORGANIC ACIDS This invention relates to a method for the formation of metallic complexes of organic acids containing water, ammonia or other small, protic acid, Lewis base donor molecules such as HZS as a ligand, and of potential utility in a number of different technical fields by reason of their volatility, solubility in organic solvents, eg. in oil and petroleum, and reactivity.

In our previous applications EP-A-0317087 and EP-A-0407121 we have disclosed a method for the preparation of Lewis base complexes of alkali, alkaline earth and transition metal salts of the general formula (MxX.nL)y, where M is the metal cation, X is an anion eg. Cl NCS , BFq, , PFg , Cl etc, L is an aprotic Lewis base, eg hexamethyl phosphoramide (HMPA), tetramethylethylenediamine (TMEDA) or pentamethyldiethylenetriamine (PMDETA), x is the valency of the anion X, m is the valency of the cation M, unless x = m, whereupon both become unity, n is an integer, usually having the value 1,2,3 or 4 and y is an integer of up to infinity, depending upon the degree of oligomer or polymer formation in the complex.In general those complexes are formed by reacting a source of the metal M, usually the elemental metal, a metal hydride, a metal alkyl or, in the case of magnesium, a Grignard reagent, with an anhydrous ammonium salt of the anion X under anhydrous conditions in an hydrocarbon solvent, especially an aromatic hydrocarbon such as toluene, containing the aprotic electron-donating organic ligand (Lewis base) L. The reaction proceeds smoothly at or just above room temperature, and the product complex, usually in crystalline form with a well-defined melting point, can be recovered from the reaction mixture eg. by refrigeration.

The above process is particularly applicable to the production of lithium salt complexes of the formula (LixX.nL)y, where X, L, x, n and y are as above defined. Typical such complexes, the preparation of which is described in EP-A-O 317087, are (LiCl.HMPA), (LiNCS.TMEDA) infinity and (LiNCS.2HMpA)2.

In EP-A-O 407121 this route has been extended to similar alkaline earth metal complexes, rare earth metal complexes and transition metal complexes, eg. the complexes: La(NCS)3.4HMPA, CaCl2.3HMPA, MgC12.2TMEDA, Ba(NCS)1.4HNPA and MnBr.2HMPA.

In J. Chem. Soc., Chem. Commun., 1990, Issue No. 8, p643, Com.

0/00262C, the present inventors and others also disclosed the preparation of the first known lithiated organic compound containing water as a ligand, viz the preparation of 2 - mercaptobenzoxazolyl (tetramethyethylenediamine) lithium monohydrate

(TMEDA).HZO. X-ray analysis has shown the complex to be a monomeric aquo-lithium complex containing a tetra-coordinated lithium atom coordinated by the two N-atoms of the TMEDA, the N-atom of the heterocyclic mercaptobenzoxazolyl ring and by the O-atom of the H2O ligand molecule.That hydrated complex was obtained by reacting nbutyl lithium with 2-mercaptobenzoxazole in the presence of toluene containing TMEDA to produce the anhydrous 2-mercaptobenzoxazolyl lithium TMEDA complex and adding the stoichiometric amount of water to the complex, ie. by the route:

toluene n-BuLi + t%MOC(.. .S).. .NH CHOC( ). . ..S)Li. (TMEDA) TMEDA (anhydrous Li complex) + + H20 C6HOC(. . S).. .Ni. (TMEDA).H > O (hydrated complex) As indicated, such hydrated complexes are of interest in a variety of different technical fields because of their oil-solubility, reactivity and volatility, and have potential utility in lubricating oil and gasoline applications as lithiated oil-soluble soaps, as lithiated drug delivery systems, as lithiating reagents and coating agents in the ceramic and semi-conductor and other fields. Not only that, but the reaction scheme outlined above is potentially applicable to a wide range of metal salts of other organic compounds RH where 14 is an "active" hydrogen atom replaceable by the metal M and R is an organic group.Generally these organic compounds (or acids) will be of the form Y-(R')-XH where X and Y are both electron-withdrawing centres independently consisting of or containing N, O or S and R' is (i) an aliphatic, aromatic or heterocyclic ring system, (ii) a hydrocarbon or other chain system, or (iii) carbon attached to (i) or (ii) above or to hydrogen. Y and XH need not necessarily be bonded to the same carbon atom in R'; however, once X is bound to a metal atom, Y must be oriented such that, in the absence of the protic Lewis donor it readily forms a dative bond to the same metal atom whilst in the presence of the protic Lewis donor- the group Y adopts a slightly displaced orientation to admit the ligand which becomes hydrogen bonded to the Y group.

However, a specific drawback of that route to hydrated Lewis base complexes of metal salts of organic acids is the well known water sensitivity of lithiated organic species and their recognised tendency to undergo ready hydrolysis in the presence of water to regenerated organic acid and LiOH. (Advanced Inorganic Chemistry, 4th Ed., Wiley, New York, 1980, p266; Organolithium Methods, Academic Press, London, 1988; and Preparative Polar Organometallic Chemistry, Springer, Berlin, 1988). In the aquation, therefore, of the 2 - mercaptobenzoxazolyl lithium TMEDA complex, the addition of water has to be controlled to the precise stoichiomett-ic amount, which in anything other than controlled laboratoly experiments is almost impossible to achieve.

Also, the yields of the reaction are low. This may be due to a phase transfer problem in that the added water (as opposed to that formed in situ by protonation) in accordance with the present invention has to enter the toluene phase before it can possibly react.

However, it has now been discovered that such complexes can be prepared in high yield and at room temperature by an alternative route starting with a solid, preferably an anhydrous metal salt MzZm Here M is the metal, Z a partly or wholly deprotonated form of a small, protic Lewis base, m is the valency of the metal and z is the number of protons removed from the small Lewis base, typically 1. Where m = z both become unity. This metal salt may be reacted with the organic acid under anhydrous conditions in an aromatic hydrocarbon solvent, preferably toluene, and preferably in the presence of a (usually aprotic) electron donor (Lewis base). The reaction proceeds smoothly at or just above room temperature, and the product may be readily recovered, usually in crystalline form, by cooling, eg. by refrigeration, of the reaction solution. The reaction may be represented (by the following non-limiting examples) as follows:

Anhydrous toluene M(OH)x + xRH. ARxM.nL.xHzO (Metal hydroxide) (Organic Acid) nL (Aquo-complex) or

anhyd.toluene MO + 2RH > R2M.nL.HO nL or anhyd.toluene M1O + 2RH b(RM)2.nL.HO nL or anhyd.toluene M203 + 6RH : (RM).nL.3H20 nL where M is the metal RH is the organic acid L is the Lewis base n is O or a whole number, usually 1,2,3 or 4.

The reaction may also be carried out using metal amides, metal hydrosulfides, metal selenides or metal methoxides as the starting reagent in place of the hydroxide or oxide, to give ammino, sulfhydr-o-, hydroseleno or methanol complexes containing ammonia, hydrogen sulfide, hydrogen selenide or methanol as a protic Lewis base ligand, eg. the reaction:

anhyd.toluene HNH2 + RH ? nL.NH3 MNH2 + RH .

nL (ammino complex) or

anhyd . toluene MSH + RH , RM.nL.H2S nL (sulfhydro complex) or anhyd. toluene MSeH + RH RM. ARM.nL.HZSe nL or anhyd. toluene MOCHA + RH RM.nL.CH30H ni The aquo, ammino, sulfhydro, hydroseleno and methanol complexes produced by the above route are recoverable from the reaction solution by cooling (refrigeration), generally as crystalline solids, which can be purified and recrystallised by standard procedures to produce substantially pure complexes in crystalline form.The complexes are generally soluble in organic solvents and are highly reactive, thus providing a potential reactive metal source for reactions in organic media. Upon heating in vacuo they lose the small protic Lewis base ligand and revert back to the aprotic Lewis base complex (RM.nL) featuring dative bonding between Y and M.

The reaction appears to be applicable to all the main group metals eg. the alkali metals, the alkaline earth metals, and to the transition metals and rare earth metals. Of particular interest are the alkali, alkaline earth and rare earth metal complexes, such as the complexes of lithium, magnesium, calcium, strontium, barium, lanthanum, yttrium, europium etc. Also of potential interest for various industrial and therapeutic applications are the complexes of lead, molybdenum, manganese and aluminium.

The organic compounds (RH) applicable in the process of the invention all have the common characteristic of an acidic hydrogen atom within the group XH and at least one other electronegative group (Y) e.g. a carbonyl oxygen atom ( C=O) a thione gr-oup C=S) or an imide (=NH) group. Thus, organic compounds applicable in the present invention include organic compounds having an acidic grouping of the formula:

Where X and Y are each 0, S or NH and may be the same or different.

Within organic compounds of type i) are, of course, the carboxylic acids, i.e. organic compounds containing the grotp:

Of interest here are the aliphatic carboxylic acids e.g. acetic, propionic, up to and including the longer chain fatty acids eg. lauric, stearic, oleic, and dicarboxylic acids such as succinic, malonic etc.

Within organic compounds of type ii) are readily enolisable compounds such as acetylacetone : CH3C(O)CH2C(O)CHj, hexafluoroacetylacetone: CF3C(O)CH2C(O)CF3 and tetramethyiheptanedione : t.BuC(O)CH2C(O)t.Bu.

Most preferred are acids of type iii) especially where the

group forms part of a heterocyclic ring. Typical heterocyclic acids of this type are

Succinimide

2 - mercaptobenzoxazole

2 - mercaptopyrimidine 2 - mercaptothiazoline

2 - mercaptobenzimidazole

2 - oxobenzoxazole

Cytosine

Thymine

Uracil Guanine Adenine X-r-ay crystallographic studies of the complexes show a coordination pattern which is characteristic of all the complexes produced by the method of the invention, ie. the insertion of the protic Lewis base ligand (H20, NH3, H2S, H2Se or MeOH) between the metal atom and the electronegative group (Y) e.g. the carbonyl oxygen or sulfur atom with a displacement of the electronegati group (Y) away from the metal atom (M), and with hydrogen bonding between the protic Lewis base [igand and the electronegative group Y, and a donor ligand bond between the aprotic Lewis base ligand and the metal cation. The insertion of the aprotic Lewis base ligand thus usually completes a 6membered coordination ring, which appear-s to be one of the factors contributing to the stability of the complex. This would also appear to account for the greater stability of complexes formed from preferred heterocyclic acids, ie. the stabilization of the acid grouping as part of a heterocyclic ring.The characteristic six-membered coordination ring established in the complexes of this invention may be illustrated, in the case of the lithiated aquo-complexes, by the following twodimensional representation:

where - - - - represents a hydrogen bond and

represents a donor ligand bond.

Similar structures may be drawn for metal atoms other than lithium, for organic compounds other than 2 - mercaptobenzoxazole containing the necessary active hydrogen atom, and for the other protic Lewis base ligands NHj, 1jS, H2Se and CiI?t)H in place of H2O.

For additional stability and organic solubility, the complexes produced in accordance with the invention preferably also, and as already indicated, contain an electron donating organic ligand molecule, or Lewis base, L. As the organic ligand any of those previously mentioned may be used, ie. HMPA, TMEDA, PMDETA etc. Other suitable ligands include (N,N'-dimethylpropylidene urea (DMPU), viz the compound:

diethylether, 1,2-dimethyloxyethane (glyme), bis (2 - methoxyethyl) ether (diglyme), dioxan, tetrahydrofuran and dimethylimidazole (DMi).

ft is to be understood, however, that this listing is by no means exhaustive and other suitable organic electron donating organic ligands (Lewis bases) will be apparent to those skilled in the art. Usually the complexes will contain from 1-5 organic ligand molecules, ie. n will have a value of from 1-5, usually 1 or 2, and from 1 to 2 small protic Lewis base ligand molecules, ie. HZO, NQ, QS, H1Se or CH;OH.

In broad outline, therefore, the present invention comprises a method for the preparation of metallic salt coordination complexes of a metal M and an organic compound RH having an active (acidic) hydrogen atom adjacent an electronegative centre in the organic group R, and which is reactive with the metal M to form a salt RM, and which contains a small protic Lewis base ligand such as QO, NHi, H2S, H2Se or CH30H coordinating the metal cation M in the said salt, which comprises reacting MZ, a solid, substantially anhydrous oxide, hydroxide, amide, sulphide, selenide or alkoxide of the metal M under substantially anhydrous conditions with the organic compound RH in the presence of aromatic hydrocarbon solvent optionally containing a usually aprotic organic donor ligand (Lewis base), and recovering from the reaction mixture a coordination complex of the formula RM.nZI!.pL where RM represents the metal salt, ZH represents the small protic Lewis base ligand coordinating the metal cation M and hydrogen bonded to an electronegative centre in R, n is a whole number indicating the number of small protic Lewis base ligand molecules (ZH) coordinating the metal cation M in the complex, L is the optional usually aprotic organic electron donor (Lewis base) and p is O or a whole number indicating the number of such organic ligand molecules coordinating the metal cation M in the complex.

The reaction process of the present invention is carried out in an anhydrous aromatic hydrocarbon solvent, preferably toluene, using a solid substantially anhydrous metal salt of a deprotonated protic Lewis base donor and the stoichiometric amounts of the organic reactant and, in the preferred case, of the Lewis base. The reaction proceeds smoothly at room temperature or with gentle warming eg. up to 100C, and the product complex recovered as a crystalline solid upon cooling the reaction mixture, possibly with refrigeration.

The method of invention and typical complexes obtained thereby are illustrated by the following examples: EXAMPLE 1 Preparation of barium-containina aquo complex:

Solid anhydrous barium hydroxide (0.86g Smmol) was added to a solution of 2 - mercaptobenzoxazole (1.51g 10mmol) and HMPA (1.79g 10mmol) in toluene (20mL). After stirring for 5 minutes, most of the Ba(OH)2 had dissolved. On further stirring a white precipitate was formed, which dissolved on heating, and formed white crystals upon cooling. These can be isolated and identified as the complex

Upon heating this aquo complex, the complex

3HMPA is obtained, the crystal structure of which is shown in Figure 1 of the accompanying drawings.The crystal structure shows the 7coordination of the central Ba atom by the two N-atoms and the two S atoms of the 2 - mercaptobenzoxazole (Ox) and the O-atoms of the three organic ligands, HMPA. In the aquo-complex the two sulfur atoms of the anhydrous complex are displaced by the ligand water molecules which coordinate the Ba atom on opposite sides, with hydrogen bonds to the two sulfur atoms. This type of structure (but using Ca instead of Ba) is described in Example 2.

EXAMPLE 2 Preparation of the calcium-containing aquo complex:

Solid calcium hydroxide (99% + anhydrous; 0.37g. Smmol) was added to a solution of 2 - mercaptobenzoxazole (1.51g 10mmol) and HMPA (3.58g 20mmol) in toluene (20mL). After stirring for 5 minutes, most of the Ca(OH)2 had dissolved. On further stirring (15 minutes) an offwhite precipitate formed. This redissolved on heating.Overnight cooling of the solution then gave colourless crystals of UC4H0C(-..MM.S...N2Ca.2HMPA.2H2Q [yield 3.31g. 90%; m p 104-1060C; correct C, H, N, P analyses; IR (Nujol mull)#(O-H) of -2 at 3288 (s), 3260(w), 3150 (s) cmD;l 1H NMR (C6D6, 250MHz, 25nC) 5 7.51 (m.1H), 7.13 (m, 1H), 6.96 (m, 1H), 6.84 (m, 1H), 4.68 (s.2H of H20), 2.21 (d. 1814 of HMPA. J 9.6Hz)].

The crystal structure of the aquo-complex is shown in Figure 2.

of the accompanying drawings. In this complex the crystal structure shows the coordination of central calcium atom Ca(1) by the two N-atoms N(1) and N(2) of the 2 - mercaptobenzoxazole molecules C (1) - C(7) and C(8) - C(14), the two oxygen atoms 0(3) and 0(4) of the two HMPA ligands, and by the two oxygen atoms 0(5) and 0(6) of the two ligand water molecules, which are hydrogen bonded to Lile two sulfur atoms S(1), S(2) of the two acid molecules. In two dimensions, the structure may be represented as

which shows more clearly the hydrogen bonding of the water molecules into a 6-membered ring with the Ca and S atoms.

EXAMPLE 3 Direct synthesis of theaq~uo-complexes (1)

Solid anhydrous lithium hydroxide (0.24g Smmol) was added to a solution of 2 - mercaptobenzoxazole (1.51g lOmmol) containing HMPA (1.79g lOmmol) in toluene (20ml) and stirred until the lithium hydroxide had dissolved. Refrigeration of the solution precipitated white crystals, mp. 99-1030C. Product analysis corresponds to the allocated formula (1)

The hemihydrate (2) is obtained by heating the aquo complex (1) to obtain the complex

forming a co-solution of the anhydrous complex (3) and the aquo-complex (1) in toluene, and recrystallizing.

The product obtained is the hemihydrate (2) [C6H4OC(...S)...NLi.HMPA]2H2O mp 105-1080C. Satisfactory analyses (C,H,Li,N,P) were obtained for all samples.

IR (Nujol mull) spectra include O-H stretching bands centred at 3538, 3358, 3170 cml for (1) and at 3397, 3351, 3147 cml for (2); such bands are not found in the spectrum of (3).

1H NMR (250MHz, 250C): (1) (C6D6)6 7.96 (1H,m), 7.19 (4H, including H20, m), 6.19 (1H,m), 2.23 (18H of HMPA, d, J 9.5Hz); (1) (C2D6SO) 5 centred 6.9 (4H, C6Hi, broad m), 3.58 (2H, H2O, s), 2.51 (18H of HMPA, d, J 9.4Hz); (2) (C6D6) 6 7.67 (2H,m), 7.20 (6H, including HZO, m) 6.87 (2H,m) 2.25 (36H of HMPA, d, J 9.5Hz); (1) (C2D6SO)o 7.05 (4H,m), 6.91 (2H,m), 6.82 (2H,m), 3.46 (2H, H2O, s), 2.50 (36H of HMPA, d, J 9.5Hz); (3) (c,u,)s 7.84 (111,m), 7.17 (1H,m), 7.07 (1H,m), 6.87 (1H,m), 2.26 (18H of HMPA, d, J 9.5Hz).

Crystal data: (1), C26H48N8O6P2S2Li2, M = 708.7, monoclinic, space group P 2t/c, a = 11.888 (3), b = 10.680 (2), c = 15.724 (3)A, ss = 108.58 (2)0, U = 1892.3 (7) A3, z = 2, De = 1.244g cm3, F (000) - 752, Cu-Ka radiation, = 1.54178A, p = 24.44 cml; (2) CZ6Hi6N805P2S2Li2, M = 690.95, monoclinic, space group P 21/a, a = 15.985 (2), b = 15.008 (2), c = 16.004 (2)A, ss = 104.36 (1)0, U = 3719.3(8)A3, = 4, Dc = 1.233g cm F (000) = 1464, Cu-Ka radiation, = 1.54178A, p = 23.53 cm1.

From the above data, the crystal structure of (1) has been determined and is shown in Figure 3 of the accompanying drawings. As shown, the complex is dimeric having two 4-coordinated lithium atoms Li(1) and Li(1a) coordinated by the N-atoms N(1) and N(la) of the 2mercaptobenzoxazole (Ox), by the two O-atoms 0(11) and O(11a) of the HMPA ligands and by the two O-atoms 0(2) and 0(2a) of the water molecules present as inorganic ligands hydrogen bonded to the two Satoms S(1) and S(1a) of the Ox-moiety.

The crystal structure of the hemihydrate is shown in Figure 4.

EXAMPLE 4 Preparation of

Following the procedure of Example 3a), solid anhydrous lithium hydroxide was reacted in toluene with equimolar quantities of 2mercaptobenzoxazole and TMEDA. The product crystals recovered by refrigeration have amp. 119-121 C and a product analysis corresponding to the assigned formula

The complex has the crystal structure shown in Figure 5 which shows the 4-coordination of the Li cation by the two N-atoms N(2) and N(3) of the bidentate TMEDA ligand, by the N-atom N(1) of the acid anion and by the O-atom 0(2) of the water molecule, the whole structure being stabilised by the hydrogen bonding of the water molecule to the S-atom S(1) of the anion.

EXAMPLE 5 Preparation of Na(HFAcAc).DMI.H2Q Sodium hydroxide is reacted with hexafluoroacetylacetone (HFAcAc:CF3C(O)CH2C(O)CFY3) in toluene in tie presence of DMI. The crystalline aquo-complex Na(HFAcAc).DMI.HZO is recovered from the reaction mixture by refrigeration.

EXAMPLE 6 Preparation of Ca(TMHD)2.2JMPU. 2HO Calcium hydroxide (0.57g 10.0mmol) was reacted with (3.69g 20.0mmol) tetramethylheptanedione (TMHD) in toluene containing (2.6g 20.26mmol) dimethyl-2-oxo-pyrimidine (DMPU) to obtain the aquo-complex Ca(TMHD)Z.2DMPU.2H20 as a crystalline product.

EXAMPLE 7 Preparation of Ba(TMHD)2DMI.3H2~ (1.90g 10.0mmol) Ba(OH)2.H20 was reacted with (3.69g 20.0mmol) TMHD in toluene in the presence of (2.29g 20.0mmol) DMI to obtain the aquo-complex Ba(TMHD)2. DMI.3H20 as a crystalline product.

EXAMPLE 8 Preparation of

using lithium oxide 0.15g (5mmol) Li20 was added to a solution of 1.8ml HMPA and 1.512g 2-mercaptobenzoxazole in 10ml toluene. On heating to 100"C on an oil bath the LiO dissolved. On cooling, the solution yielded 0.340g of crystalline

having an identical melting point and n.m.r spectrum to compound (1) prepared in Example 3.

EXAMPLE 9 Preparation of the bemi hydrosulfido complex:

0.198g (2.5mmol) of LiZS was added to a solution of 0.9ml HMPA and 0.756g 2-mercaptobenzoxazole in 1Oml toluene. On heating to 100"C on an oil bath for 12 hours, practically all the Li2S dissolved. The reaction solution was filtered hot and refrigerated for 48 hours to yield 0.261g of brown crystals. Preliminary n.m.r. studies are consistent with the assigned formula

The above results herald, we believe, enormous synthetic advances and excursions into fields as diverse as metal oxide film deposition and bioinorganic chemistry. Firstly, they target organic "acid" precursors: ones of type Y-R'-XH [R' equalling e.g.CH in a ring or (CH2)n in a chain] with pKa approximately that of the protic Lewis base and with two electronegative centres X and Y drawn from combinations of or containing N, O or S. One centre (X) will be metallated and the other (Y) will hydrogen-bond to the assembled H20 or similar small protic Lewis base molecule. Secondly, the direct synthesis of aquo complexes by assemblage of H20 ligands using solid metal hydroxides offers vast scope. In the system nYR'XH (organic acid) + xL (ligand) + solid M(OH)n, for example, R', L and/or x, M (thus n) can be varied.

So too can the reaction stoichiometry, eg. YR'XH + M(OH) [1:1 instead of 2:1] gives R'MOH.H2O, i.e. hydroxy aquo complexes; their dehydration should give "anhydrides" with R'M-O-MR' linkages. Use of metal oxides rather than hydroxides promises aquo variations, e.g. YR'XH + MO R'IM.HlO. H20. It should also be possible to assemble other small complexants by this direct method, e.g. NH3 by reactions of YRXH with solid metal amides. Thirdly, such assembled ligands (hay, NH3, etc) are likely to be activated, both by their complexation and by their hydrogen-bonding to We centres of the anionic ligands. Thus, their metallation by M' (not necessarily the same as M) will be enhanced, providing volatile, complexed metal and mixed-metal oxides, amides, etc. Finally, the products without the small protic Lewis base themselves are set up to act as dual-purpose ligands: they have metal centres in low coordination environments, and S6(Y in general) arms which can be displaced by incoming molecules so that the coordination number and steric crowding of the metal is not increased. Because of their hydrocarbon solubility such products are also of potential interest as oil or petroleum soluble metal soaps and dispersants in hydrocarbon based products such as gasoline and lubricating oils.

Claims

CLAIMS:

1. A method for the preparation of metallic salt coordination complexes of a metal M and an organic compound RH having an active (acidic) hydrogen atom adjacent an electronegative centre in the organic group R and which is reactive with the metal M to form a salt RM, and which contain a small protic Lewis base ligand L selected from HZO, NH3, H2S, QSe and CH1OH coordinating the metal cation M in said salt, which comprises reacting a solid, substantially anhydrous compound of the deprotonated small protic Lewis base donor ligand and the metal M and representable by the formula MZ under substantially anhydrous conditions with the organic compound RH in the presence of aromatic hydrocarbon solvent and optionally an organic donor ligand (Lewis base), and recovering from the reaction mixture a coordination complex of the formula RM.nZH.pL, where RM represents the metal salt, ZH represents the small protic Lewis base ligand coordinating the metal cation M and hydrogen bonded to the electronegative centre in R, n is a whole number indicating the number of small protic Lewis base ligand molecules coordinating the metal cation M in the complex, L is the optional organic electron donor (Lewis base) and p is O or whole number indicating the number of organic ligand molecules coordinating the metal cation M in the complex.

2. A method according to Claim 1, wherein the metal M is a main group metal, a transition metal, or a rare earth metal.

3. A method according to Claim 2, wherein M is a main group metal selected from the alkali metals and the alkaline earth metals.

4. A method according to Claim 1, 2 or 3, wherein the metalcontaining reagent MZ is an oxide, hydroxide, amide, sulphide, hydrosulphide, selenide, hydroselenide or alkoxide of the metal M.

5. A method according to any one of Claims 1 to 4, wherein the organic reactant comprises an acidic grouping of the formula:

where X and Y each represent SH, O or S, thereby to produce a coordination complex of the metal M comprising the structure:

where M = the metal cation; L = Lewis base; n = O or ZH = the small protic Lewis base ligand H2O, NH3 H2S, QSe or CHrOH coordinating the metal cation M; - - - - - represents a hydrogen bond between the inorganic aprotic Lewis base ligand ZH and the group Y; and

represents a donor ligand bond between the inorganic ligand ZH and the metal cation M and, when n is a whole number, between the usually protic Lewis base organic ligand L and the metal cation M.

6. A method according to Claim 5, wherein the organic acid is a heterocyclic organic acid containing the group

as part of the heterocycle, where Y is NH, O or S.

7. A method according to Claim 6, wherein the or-ganic acid is 2mercaptobenzoxazole.

8. A method according to any one of Claims 1-7, wherein the reaction is carried out in the presence of an organic electron donor (Lewis base) selected from HMPA, TMEDA, PMDETA, DMPU and DMI.

9. A method according to any one of Claims 1-8 wherein the reaction is carried out in toluene as the aromatic hydrocarbon solvent.