Synthesis of a highly enantiomerically enriched silagermane and selective cleavage of the Si-Ge bond with lithium

(R)-PhMe(CH2NC5H10)SiGeMe3, the first enantiomerically pure silagermane with stereoinformation at the silicon, was synthesized via a lithiosilane with retention of configuration. Further reaction with lithium resulted in unanticipated silicon-germanium bond cleavage to form PhMe(CH2NC5H10)SiLi, although the disilane (R)-PhMe(CH2NC5H10)SiSiMe3 undergoes silicon-phenyl bond cleavage. A trapping reaction with pentamethylchlorodisilane occurred with retention of configuration. DFT calculations on the model systems PhH2SiSiH3 and PhH2SiGeH3 indicate a stepwise, dissociative electron transfer mechanism for the silicon-element bond cleavage.