Synthesis and Structures of Sterically Encumbered Group 14 Monolithio Compounds and Unexpected Differences in Their Reactivity

Group 14 monolithio compounds with sterically encumbered terphenyl ligands, ArM₁₄(SiHMe₂)₂Li [M₁₄ = Si, Ge, Sn; Ar = 2,6-bis(2,6-diisopropylphenyl)phenyl and 2,6-bis(2,4,6-triisopropylphenyl)phenyl], were prepared by transmetalation reactions of ArM₁₄(SiHMe₂)₃ with methyllithium, the structures of which were established by X-ray diffraction analysis. The monolithiosilanes and monolithiogermanes reacted with iodomethane and trichlorophosphane to afford the corresponding monomethylated and dichlorophosphane-substituted derivatives, respectively. However, surprisingly, the reactions of monolithiostannanes with iodomethane and trichlorophosphane provided trimethylstannane and trichlorostannane, respectively.