MIXED-LIGAND IMIDAZOLATES OF NI(II), PD(II) AND PT(II) USING ME(3)SI-IMIDAZOLE 2-METHYL IMIDAZOLE AS A REAGENT/

The title reagents are a potent source for transforming metallic subst rates with an M-Cl bond to the corresponding covalent metal-imidazolat e bond. Reactions of [(eta(5)-Cp)Ni(Ph(3)P)I] and [Pt(Ph(3)P)(2)Cl-2] proceed with complete substitution of halogen giving quantitative yiel ds of [(eta(5)-Cp)Ni(Ph(3)P)L] (L = imidazolate, Iz, or 2-methylimidaz olate, MeIz) and [Pt(Ph(3)P)2(l)2], respectively, while [Pd(L')(2)Cl-2 ] (L' = MeCN or Ph(3)P) affords [Pd(L')(L)Cl] with release of one mole equivalent of the supporting ligand, MeCN or Ph(3)P. Physicochemical data suggest an oligometric and non-electrolytic nature of the compoun ds in which the M-N(pyrrolic) bond is of considerable p character. Mag netic moment and spectroscopic data suggest that NI(II) is five-coordi nated and the solid paramagnetic monomer loses Ph(3)P in DMSO solution forming a diamagnetic imidazolate bridged dimer [(eta(5)-Cp)NiL](2). The square planar geometry for Pd(II) compounds is attained through an imidazolate bridged dimeric structure whereas Pt(II) compounds are sq uare planar monomers.