Hydrogen gas formation from the photolysis of rhenium hydrides – mechanistic and computational studies

Abstract

The photolysis of 4,4′-disubstituted, 2,2′-bipyridine fac-Re(bpy)(CO)₃H derivatives produces stoichiometric H₂ gas. The rate of production varies greatly depending on the electronic nature of the disubstituted bipyridine (bpy) with halogenated substituents increasing the rate. Isotope labeling studies along with B3LYP geometry optimization DFT modeling studies indicate a mechanism involving a Re–H–Re bridging complex that leads to a dimeric Re–Re(η²-H₂) state prior to dissociating H₂ gas.