Carbon-Phosphorus Coupling from C^N Cyclometalated Au(III) Complexes

With the aim of exploiting new organometallic species for cross-coupling reactions, we report here on the Au(III)-mediated Caryl-P bond formation occurring upon reaction of C^N cyclometalated Au(III) complexes with phosphines. The [Au(C^N)Cl2] complex 1 featuring the bidentate 2-benzoylpyridine (CCON) scaffold was found to react with PTA (1,3,5-triaza-7-phosphaadamantane) under mild conditions, including in water, to afford the corresponding phosphonium 5 via C-P reductive elimination. A mechanism is proposed for the title reaction based on in situ 31P1H NMR and HR-ESI-MS analyses combined with DFT calculations. The C-P coupling has been generalized to other C^N cyclometalated Au(III) complexes and other tertiary phosphines. Overall, this work provides new insights into the reactivity of cyclometalated Au(III) compounds and establishes initial structure-activity relationships to develop Au(III)-mediated C-P cross-coupling reactions.