Complexes derived from 4-(diphenylphosphino)benzoic acid and related ligands that contain mixed-metal assemblies of palladium(II) or gold(I) in combination with the multiply bonded dirhenium(II) unit

The reactions of cis-Re-2(mu-O2CCH3)(2)Cl-2(mu-dppm)(2) (dppm = Ph2PCH2PPh2) with substituted benzoic acids of the type 4-XC6H4CO2H (X = Ph2P, Ph2P(O), Ph2P(S) or Ph2P(O)CH2) and with quinoline-4-carboxylic acid afford the complexes cis-Re-2(mu-O2CC6H4-4-X)(2)Cl-2(mu-dppm)(2) (X = Ph2P (1), Ph2P(O) (2), Ph2P(S) (3) or Ph2P(O)CH2 (4)) and cis -Re-2(mu-O2CC10H6N)(2)Cl-2(mu-dppm)(2) (5). Similar reactions of trans-Re-2(mu-O2CCH3)(2)Cl-2(mu-dppE)(2) (dppE = Ph2PC(=CH2)PPh2) with 4-Ph2PC6H4CO2H and quinoline-4-carboxylic acid give trans-Re-2(mu-O2CC6H4-4-PPh2)(2)Cl-2(mu-dppE)(2) (6) and trans -Re-2(mu-O2CC10H6N)(2)Cl-2(mu-dppE)(2) (7), respectively. The ability of the unbound ligand functionality on the mu-carboxylate ligands in complexes 1-7 to be used to form mixed-metal complexes is demonstrated by the reactions of I and 6 with AuCl(tht) (tht = tetrahydrothiophene) to give cis-Re-2(mu-O2CC6H4-4-PPh2)(2)Cl-2(mu-dppm)(2)(AuCl)(2) mu-dppm)(2)(AuCl)(2) (8) and trans-Re-2(mu-O2CC6H4-4-PPh2)(2)Cl-2(mu-dppE)(2)(AuCl)(2) (9). In addition, the reaction of 1 with PdCl2(COD) affords the Re2Pd2 complex cis-Re-2(mu-O2C6H4-4-PPh2)(2)Cl-2(mu-dppm)(2)(Pd2Cl4) (10), in which the planar [(P)ClPd(mu-Cl)(2)PdCl(P)] unit has the unusual cis planar structure. An alternative method for preparing mixed-metal Re2Pd2 assemblies is shown by the reaction of cis -Re-2(mu-O2CCH3)(2)Cl-2(mu-dppm)(2) with cis-PdCl2[(Ph2PCH2)(2)N-4-C6H4CO2H] to produce the complex cis-ReCl2(mu-dppm)(2)[mu-O2CC6H4-4-N(CH2PPh2)(2)(PdCl2)](2) (11) in which the mononuclear cis-PdCl2(P)(2) units are retained. The structures of 1, 7 and 10 have been established by X-ray crystallography. (C) 2002 Elsevier Science B.V. All rights reserved.