Synthesis of BICAAC Supported Si(III) Radicals and a Silylone via Reduction Route From BICAAC-Si(IV) Precursors.

Past one decade has witnessed a tremendous growth in the field of carbene stabilized low-valent silicon compounds unravelling very exciting properties of these molecules. Herein, we have employed a bicyclic (alkyl)(amino)carbene, (BICAAC) to explore the low-valent chemistry of silicon. The reduction of bicyclic (alkyl)(amino)carbene-SiCl complex, [(BICAAC)SiCl] (1) with KC afforded low-valent Si complexes, including Si(III) radical [(BICAAC)SiCl] (2) and a complex with silicon center in a formal zero-valent state, [(BICAAC)Si] (3). Similarly, the reduction of in-situ generated BICAAC adduct of MeSiCl with one equivalent of KC led to the formation of [(BICAAC)SiMeCl] (4) complex having an unpaired electron. These complexes have been characterized by IR, UV-Vis., NMR, HRMS, EPR and their solid-state structures were also elucidated by single crystal X-ray crystallography. Further, DFT calculations revealed the lower energy singlet state for complexes 1, 3 and doublet state for complexes 2, 4.