Synthesis and Properties of Aryl‐ and Amino‐Substituted Dibenzo[b,e]phosphindolizines

Dibenzo[b,e]phosphindolizine oxides with five different aryl groups and a diphenylamino group at the 10-position were synthesized by the Suzuki-Miyaura cross-coupling reaction and the Buchwald-Hartwig amination reaction of 10-chlorodibenzo[b,e]phosphindolizine. The molecular structures and properties of the products were elucidated by X-ray crystallographic analysis, UV-vis spectroscopy, and electrochemical analysis. Dibenzo[b,e]phosphindolizines with p-(diphenylamino)phenyl and diphenylamino groups have smaller HOMO-LUMO gaps and higher HOMO energy levels than derivatives with methoxy and trifluoromethyl groups and without an amino group. The substituent effects were also investigated by theoretical calculations.