Za. Siddiqi et al., MIXED-LIGAND IMIDAZOLATES OF NI(II), PD(II) AND PT(II) USING ME(3)SI-IMIDAZOLE 2-METHYL IMIDAZOLE AS A REAGENT/, Synthesis and reactivity in inorganic and metal-organic chemistry, 23(10), 1993, pp. 1735-1752
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.