Conformational switching through the one‐electron reduction of an acridinium‐based γ‐cationic phosphine gold complex

Our efforts in the chemistry of gold complexes featuring ambiphilic phosphine-carbenium L/Z-type ligand have led us to consider the reduction of the carbenium moiety as a means to modulate the gold-carbenium interaction present in these complexes.  Here, we show that the one-electron reduction of [( o -Ph 2 P(C 6 H 4 )Acr)AuCl] + (Acr = 9- N -methylacridinium) produces a neutral stable radical, the structure of which shows a marked increase in the Au - Acr distance.  Related structural changes are observed for the phosphine oxide analog [( o -Ph 2 P(O)(C 6 H 4 )Acr] + , the reduction of which also interferes with the P=O - carbenium interaction.  These structural effects, driven by a reduction-induced change in the electrostatic potential profile of the compounds, show that the charge and accepting properties of the carbenium unit can be modulated.  These results highlight the redox-noninnocence of carbenium Z-type ligand, a feature that can be exploited to induce specific conformational changes.