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.

Carbene-Stabilized Phosphagermylenylidene: A Heavier Analog of Isonitrile

“…These compounds, representing Ge/P analogs of imines, exhibit unique (cyclo)­addition reactivity toward small molecules, clearly diverging from the behavior of traditional imines. In the pursuit of synthesizing heavier analogs of nitriles, early efforts to synthesize germylidenyl-phosphinidenes (R–GeP/R–Ge–P) consistently resulted in the formation of their head-to-tail or head-to-head dimers . However, a breakthrough came in 2019 when the Inoue group, by incorporating an additional Lewis basic N-heterocyclic carbene (NHC) at the phosphorus atom, isolated germylidenyl-phosphinidene A (Figure b) .…”