Heterobimetallic Gold/Ruthenium Complexes Synthesized via Post‐functionalization and Applied in Dual Photoredox Gold Catalysis

The synthesis of heterobimetallic Au(I)/Ru(II) complexes of the general formula syn‐ and anti‐[{AuCl}(L1∩L2){Ru(bpy)(2)}][PF(6)](2) is reported. The ditopic bridging ligand L1∩L2 refers to a P,N hybrid ligand composed of phosphine and bipyridine substructures, which was obtained via a post‐functionalization strategy based on Diels‐Alder reaction between a phosphole and a maleimide moiety. It was found that the stereochemistry at the phosphorus atom of the resulting 7‐phosphanorbornene backbone can be controlled by executing the metal coordination and the cycloaddition reaction in a different order. All precursors, as well as the mono‐ and multimetallic complexes, were isolated and fully characterized by various spectroscopic methods such as NMR, IR, and UV‐vis spectroscopy as well as cyclic voltammetry. Photophysical measurements show efficient phosphorescence for the investigated monometallic complex anti‐[(L1∩L2){Ru(bpy)(2)}][PF(6)](2) and the bimetallic analogue syn‐[{AuCl}(L1∩L2){Ru(bpy)(2)}][PF(6)](2), thus indicating a small influence of the {AuCl} fragment on the photoluminescence properties. The heterobimetallic Au(I)/Ru(II) complexes syn‐ and anti‐[{AuCl}(L1∩L2){Ru(bpy)(2)}][PF(6)](2) are both active catalysts in the P‐arylation of aryldiazonium salts promoted by visible light with H‐phosphonate affording arylphosphonates in yields of up to 91 %. Both dinuclear complexes outperform their monometallic counterparts.