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

Substitution reactions of labile d10 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, 1H and 13C NMR spectroscopy, IR spectroscopy, and liquid injection field desorption ionization mass spectrometry (LIFDI-MS).