Carbon-Phosphorus Coupling from C^N Cyclometalated AuIII Complexes

Abstract

With the aim of exploiting new organometallic species for cross-coupling reactions, we report here on the Au^III -mediated C_aryl -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 (C^CO N) 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 through C-P reductive elimination. A mechanism is proposed for the title reaction based on in situ ³¹ P{¹ H} 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.

Keywords: carbon-phosphorous bond; cross-coupling; density functional calculations; gold(III) cyclometalated compounds; reductive elimination.