A New Approach to the Synthesis of Unsymmetrical Disilenes and Germasilene: Unusual 29Si NMR Chemical Shifts and Regiospecific Methanol Addition

The reaction of dilithiosilanes ( i Pr 3 Si) 2 SiLi 2 ( 1a ) and ( t Bu 2 MeSi) 2 SiLi 2 ( 1b ) with diaryldichlorosilanes [Ar 2 SiCl 2, Ar = Mes (2,4,6-trimethylphenyl) and Tip (2,4,6-triisopropylphenyl)] quantitatively produced the corresponding unsymmetrical 1,1-diaryl-2,2-bis(trialkylsilyl)disilenes, Ar 2 Si Si(SiR 3 ) 2 ( 2, R 3 Si = i Pr 3 Si; 3, R 3 Si = t Bu 2 MeSi). A stable germasilene, Mes 2 Ge Si(SiMe t Bu 2 ) 2 ( 4 ), was also synthesized by the reaction of 1b with dimesityldichlorogermane. These compounds reveal unusual 29 Si NMR shifts and regioselective methanol additions.