High turnover photocatalytic hydrogen formation with an Fe(<scp>iii</scp>) N-heterocyclic carbene photosensitiser

Abstract

Herein we report the first high turnover photocatalytic hydrogen formation reaction based on an earth-abundant Fe^III-NHC photosensitiser. The reaction occurs <i>via</i> reductive quenching of the ²LMCT excited state that can be directly excited with green light and employs either Pt-colloids or [Co(dmgH)₂pyCl] as proton reduction catalysts and [HNEt₃][BF₄] and triethanolamine/triethylamine as proton and electron donors. The outstanding photostability of the Fe^III-NHC complex enables turnover numbers >1000 without degradation.