New Digermylalkenes and Digermylalkynes: [1,3]-Chlorine Shifts in Organogermanium Chemistry?

Dimesitylfluoro(trichloromethyl)germane (1) has been synthesized from difluorodimesitylgermane, chloroform, and n-butyllithium. Addition of n-butyllithium to compound 1 gave the lithium carbenoid Mes2(F)Ge−C(Li)Cl2 (2), which behaves as a synthetic equivalent of the C-dichlorogermene Mes2GeCCl2 (5). Warming 2 to room temperature afforded the 1,2-digermylalkene Mes2(F)Ge−CClCCl−Ge(Cl)Mes2 (6) possibly by an unprecedented [1,3]-Cl shift from the transient germene Mes2(F)Ge−CCl2−CClGeMes2 (8). Addition of tert-butyllithium to 6 gave bis(chlorogermyl)alkyne Mes2(Cl)Ge−C⋮C−Ge(Cl)Mes2 (9) probably via a 3-chloro-1-germaallene/(chlorogermyl)alkyne rearrangement.