Formation of Germenes from Bis(germavinylidene)

A series of germenes have been synthesized from the bis(germavinylidene) [(Me₃SiNPPh₂)₂CGe→GeC(PPh₂NSiMe₃)₂] (1). The reaction of 1 with 2,2,6,6-tetramethylpiperidine N-oxide afforded [(Me₃SiNPPh₂)₂CGe(ONCMe₂C₃H₆CMe₂)₂] (2). Germavinylidene, the dissociation derivative of 1, underwent [1 + 4] cycloaddition with azobenzene, followed by a 1,3-H shift to give [(Me₃SiNPPh₂)₂CGe(o-C₆H₄NHNPh)] (3). Treatment of 1 with benzil afforded the [1 + 4] cycloaddition compound [(Me₃SiNPPh₂)₂CGe{O(Ph)CC(Ph)O}] (4). The results showed that the germavinylidene moiety dissociated from 1 acts as a synthon for the preparation of various germenes by addition to the germanium(II) center. The molecular structures of 2−4 have been determined.