Low-Valent Si Complexes Supported by Bicyclic (Alkyl)(Amino)Carbene (MeBICAAC): Syntheses, Characterization, and Reactivity Studies

Past one decade has witnessed the tremendous growth in the field of carbenes stabilized low-valent silicon compounds owing to very exciting properties of these molecules. Herein, we have employed a bicyclic (alkyl)(amino)carbene (MeBICAAC) to explore the low-valent chemistry of silicon compounds. The reduction of bicyclic (alkyl)(amino)carbene-SiCl4 complex, [(MeBICAAC)SiCl4] (1) with KC8 afforded their low-valent Si complexes, including Si(III) radical [(MeBICAAC)SiCl3] (2) and a complex with silicon center in a formal zero-valent state [(MeBICAAC)2Si] (3). Similarly, the reduction of in-situ generated MeBICAAC adduct of Me2SiCl2 with one equivalent of KC8 leads to the formation of [(MeBICAAC)SiMe2Cl] (4) complex having an unpaired electron. All these complexes have been characterized by IR, UV-Vis., NMR (for 1), HRMS 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. The magnetic moment measurements and EPR studies were also carried out to confirm the presence of radicals in complexes 2 and 4.