Unravelling Structural Mysteries of Simple Organozinc Alkoxides.

Abstract

Simple RZnOR' alkoxides are among the first known organozinc compounds, and widespread interest in their multifaced chemistry has been driven by their fundamental significance and potential applications including various catalytic reactions. Nevertheless, their chemistry in solution and in the solid state remains both relatively poorly understood and a subject of constant debate. Herein, the synthesis and structural characterization of long-sought structural forms, a roof-like trimer [(tBuZn)3 (μ-OC(H)Ph2 )2 (μ3 -OC(H)Ph2 )] and a ladder-type tetramer [(PhZn)4 (μ-OC(H)Ph2 )2 (μ3 -OC(H)Ph2 )2 ], incorporating diphenylmethanolate as a model alkoxide ligand, are reported. Both novel aggregates are robust in the solid state and resistant towards mechanical force. By using 1 H NMR and diffusion-order spectroscopy, it is demonstrated that new RZnOR' alkoxides are kinetically labile in solution and readily undergo ligand scrambling, such as in the case of Schlenk equilibrium. The elucidated key structural issues, which have remained undiscovered for decades, significantly advance the chemistry of RZnOR' alkoxides and should support the rational design of zinc alkoxide-based applications.