Heavy alkali metal complexes of N-heterocyclic carbenes

Abstract

N-Heterocyclic carbene complexes of alkali metals (M = Na, K, Rb, Cs) were prepared from the zwitterionic trimethylsilylimidazolium borate [(C₆F₅)₃B(IDipp)SiMe₃] (1) by reaction with the corresponding alkali metal tert-butoxides MOtBu. The alkali metal complexes were isolated as tetrahydrofuran (THF) solvates of the type [(C₆F₅)₃B(IDipp)M(THF)_x, 2^M(THF)_x, and their molecular structures were determined by single-crystal X-ray diffraction analysis.