Stimuli Responsive Silylene: Electromerism Induced Reversible Switching Between Mono- and Bis-Silylene

摘要

Electromerism is a very well-known phenomenon in transition metal chemistry. In main group chemistry, this concept has only started getting attention recently. We report stimuli responsive low-valent silicon compounds exhibiting electromerism. A mixed-valent suaiminyl-silylene 1, [LSi-Si(NDipp)L] (L = PhC-(N~tBu)2), was synthesized in a single step from amidi-nate-chlorosilylene. Compound 1 has two interconnected Si atoms in formally +I and +III oxidation states. Upon treatment with Lewis acidic Cu~IX (X = mesityl, Cl, Br, I), electron redistribution occurs resulting in the formation of [{LSi(NDipp)Si(L)}-CuX], in which both silicon atoms are in the + II formal oxidation state. Removal of the copper center from [{LSi (NDipp)Si(L)}-CuX] by using a Lewis basic carbene led to reformation of the precursor [LSi-Si(NDipp)L]. Thus, the process is fully reversible. This showcases the first example of Lewis acid/base-induced reversible electromerism in silicon chemistry.