A new RuIIRhIII bimetallic with a single Rh–Cl bond as a supramolecular photocatalyst for proton reduction

A new RuIIRhIII structural motif [(bpy)2Ru(dpp)RhCl(tpy)]4+ with one halide on the RhIII center demonstrates light-driven proton reduction ability, establishing that two halide ligands are not mandatory despite all prior systems containing a cis-RhCl2 catalytic site. This new design provides a novel approach to modulate RhIII redox behavior and catalytic activity with insight into catalytic intermediates.