Photocatalytic Reduction of Nitrobenzene to Aniline by an Intriguing {Ru(CH)}-Based Heteropolytungstate.

In this paper, we have successfully synthesized a structurally novel heteropolytungstate via coordination of four {Ru(CH)} and trivacant {TeWO} clusters, formulated as CsNaH[TeWO(HO){(CH)Ru}]·12HO (). Compound inherited the strong absorption of [Ru(CH)Cl] in the visible region and {TeWO} in the UV region, providing a good basis for photocatalysis. As expected, compound showed good photocatalytic activity in the visible-light-driven reduction of nitrobenzene using NH·HO as a reductant with a yield of 99.8%, a high turnover number (TON = 330), and a high turnover frequency (TOF = 24 h). The cyclic experiment of nitrobenzene reduction indicated that compound was an effective and stable heterogeneous catalyst. Finally, the nitrobenzene reduction pathway was affirmed using condensation with azobenzene as a reaction intermediate based on control experiments.