Mononuclear Heteroscorpionate Zwitterionic Zinc Terminal Hydride: Synthesis, Reactivity, and Catalysis for Hydrosilylation of Aldehydes

Treatment
of heteroscorpionate zinc benzyloxy complex LZnOBn (1, L = (MePz)2CP­(Ph)2NPh, MePz = 3,5-dimethylpyrazolyl) with phenylsilane (PhSiH3)
gave a zinc hydride complex LZnH (2) containing a rare
terminal hydride fragment. X-ray diffraction analysis and the DFT
calculation confirm the zwitterionic structure of complex 2. The stoichiometric reaction of 2 with CS2 readily afforded a dithioformate complex LZnSCH­(S) (3) of the CS insertion into the Zn–H product. Moreover,
complex 2 was an efficient catalyst for the hydrosilylation
reaction of a series of silanes and aldehydes under mild conditions,
featuring excellent functional group tolerance. The preliminary mechanistic
study revealed that both zinc benzyloxy complex 1 and
zinc hydride complex 2 were involved in the hydrosilylation
process as the reaction intermediates.