Photolysis of Phosphaketenyltetrylenes with a Carbazolyl Substituent

Abstract

Phosphaketenes of divalent group 14 compounds can potentially serve as precursors for the synthesis of heavy multiple-bond systems. We have employed the dtbpCbz substituent (dtbpCbz=1,8-bis(3,5-ditertbutylphenyl)-3,6-ditertbutylcarbazolyl) to prepare such phosphaketenyltetrylenes [(dtbpCbz)EPCO] (E=Ge, Sn, Pb). While the phosphaketenyltetrylenes are stable at ambient conditions, they can be readily decarbonylated photolytically. For the germylene and stannylene derivatives, dimeric diphosphene-type products [(dtbpCbz)EP]2 (E=Ge, Sn) were obtained. In contrast, photolysis of the phosphaketenylplumbylene, via isomerisation of the [(dtbpCbz)PbP] intermediate to [(dtbpCbz)PPb], afforded an unsymmetric and incompletely decarbonylated product [(dtbpCbz)2Pb2P2CO] formally comprising a [(dtbpCbz)PPb] and a [(dtbpCbz)PbPCO] moiety.