Controlled Interconversion of a Dinuclear Au Species Supported by a Redox-Active Bridging PNP Ligand Facilitates Ligand-to-Gold Electron Transfer

Redox non‐innocent ligands have recently emerged as interesting tools to obtain new reactivity with a wide variety of metals. However, gold has almost been neglected in this respect. Here, we report mechanistic investigations related to a rare example of ligand‐based redox chemistry in the coordination sphere of gold. The dinuclear metal‐centered mixed‐valent Au^I–Au^III complex 1, supported by monoanionic diarylamido‐diphosphine ligand PNP^Pr and with three chlorido ligands overall, undergoes a complex series of reactions upon halide abstraction by silver salt or Lewis acids such as gallium trichloride. Formation of the ultimate Au^I–Au^I complex 2 requires the intermediacy of Au^I–Au^I dimers 5 and 7 as well as the unique Au^III–Au^III complex 6, both of which are interconverted in a feedback loop. Finally, unprecedented ortho‐selective C−H activation of the redox‐active PNP ligand results in the carbazolyldiphosphine derivative PN*P^Pr via ligand‐to‐metal two‐electron transfer. This work demonstrates that the redox‐chemistry of gold may be significantly expanded and modified when using a reactive ligand scaffold.