Reactivity of [Zn2Cp*2] toward Transition-Metal Complexes: Synthesis and Characterization of [Cp*M(ZnCp*)3] (M = Ni, Pd, Pt)

Substitution reactions of labile d(10) metal starting complexes with [Zn2Cp*(2)] (Cp* = pentamethylcyclopentadienyl) are presented. The treatment of [M(cod)(2)] (M = Ni, Pt; cod =1,5-cyclooctadiene) with stoichiometric amounts of [Zn2Cp*(2)] results in the formation of [Cp*M(ZnCp*)(3)] (M = Ni (1), Pt (2)) with the release of 1,3-cyclooctadiene. In addition to Cp* transfer reactions from zinc(I) to the transition-metal centers, the formation of compounds 1 and 2 results via redox chemical pathways: namely, the oxidation of M(0) to M(I) and the reduction of 1 equiv of Zn(I) to Zn(0). The Pd homologue [Cp*Pd(ZnCp*)(3)] (3) is obtained as a byproduct in the reaction of [Pd(CH3)(2)(tmeda)] (tmeda = N,N,N',N'-tetramethylethane-1,2-diamine) with [Zn2Cp*(2)]. Herein, various side reactions and competing redox chemical processes are involved, including the formation of [Pd(ZnCp*)(4)(ZnMe)(4)] as well as [Pd(ZnCp*)(4)(ZnMe)(2)(Zn{tmeda})]. Compounds 1-3 have been fully characterized by single-crystal X-ray diffraction, H-1 and C-13 NMR spectroscopy, IR spectroscopy, and liquid injection field desorption ionization mass spectrometry (LIFDI-MS).