Discovering the Balance of Steric and Electronic Factors Needed To Provide a New Structural Motif for Photocatalytic Hydrogen Production from Water

Ru,Rh,Ru supramolecules are known to undergo multielectron photoreduction and reduce H2O to H-2. Ru, Rh bimetallics were recently shown to photoreduce but not catalyze H2O reduction. Careful tuning of sterics and electronics for [(TL)(2)Ru(dpp)RhCl2(TL')](3+) produce active bimetallic photocatalysts (TL = terminal ligand). The system with TL,TL' = Ph(2)phen photocatalytically reduces H2O to H-2 while TL,TL' = phen,bpy or bpy,(t)Bu(2)bpy do not.