Cleavage of the Au−P Bond in Au-Substituted Phosphines

Three protocols that involve the cleavage of the Au−P bond in Au-substituted phosphines (AuPhos) have been demonstrated, namely i) direct demetallation with a strong anionic base; ii) protonation followed by demetallation with a neutral base; iii) oxidation-triggered metal migration. Specifically, direct demetallation of (CAAC)AuPPh2 (1a) (CAAC = cyclic (alkyl)(amino)carbene) with KP(TMS)2 or LiC(N2)TMS yields (CAAC)AuPTMS2 (2) or (CAAC)AuC(N2)TMS (3), respectively. Treatment of (NHC)AuPPh2 (1b) (NHC = N-heterocyclic carbene) with HOTf followed by the corresponding neutral phosphine gives scarce examples of aurophosphonium salts [(NHC)AuPHAd2][OTf] (5) and [((NHC)Au)2PPh2][OTf] (6). Oxidation of 1a or 1b with Se affords LAuSeP(Se)Ph2 (L = CAAC, 7a; NHC, 7b).