Formation of Germenes from Bis(germavinylidene)

A series of germenes have been synthesized from the bis(germavinylidene) [(Me 3 SiN PPh 2 ) 2 C Ge→Ge C(PPh 2 NSiMe 3 ) 2 ] ( 1 ). The reaction of 1 with 2,2,6,6-tetramethylpiperidine N -oxide afforded [(Me 3 SiN PPh 2 ) 2 C Ge(ONCMe 2 C 3 H 6 CMe 2 ) 2 ] ( 2 ). Germavinylidene, the dissociation derivative of 1, underwent [1 + 4] cycloaddition with azobenzene, followed by a 1,3-H shift to give [(Me 3 SiN PPh 2 ) 2 C Ge( o -C 6 H 4 NHNPh)] ( 3) . Treatment of 1 with benzil afforded the [1 + 4] cycloaddition compound [(Me 3 SiN PPh 2 ) 2 C 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.