Catalytic transfer hydrogenation of N2 to NH3 via a photoredox catalysis strategy

Inspired by momentum in applications of reductive photoredox catalysis to organic synthesis, photodriven trans-fer hydrogenations toward deep (>2 e-) reductions of small molecules are attractive compared to using harsh chemical reagents. Noteworthy in this context is the nitrogen reduction reaction (N2RR), where a synthetic photo -catalyst system had yet to be developed. Noting that a reduced Hantzsch ester (HEH2) and related organic struc-tures can behave as 2 e-/2 H+ photoreductants, we show here that, when partnered with a suitable catalyst (Mo) under blue light irradiation, HEH2 facilitates delivery of successive H2 equivalents for the 6 e-/6 H+ catalytic reduc-tion of N2 to NH3; this catalysis is enhanced by addition of a photoredox catalyst (Ir). Reductions of additional substrates (nitrate and acetylene) are also described.

Automated summary

Inspired by reductive photoredox catalysis, photodriven transfer hydrogenation reactions are attractive for deep reductions of small molecules. In this study, a synthetic photo-catalyst system was developed, enabling the catalytic reduction of nitrogen to ammonia. The reduction of other substrates was also investigated.