Thiol and H2S-Mediated NO Generation from Nitrate at Copper(II)

Reduction of nitrate is an essential, yet challengingchemicaltask required to manage this relatively inert oxoanion in the environmentand biology. We show that thiols, ubiquitous reductants in biology,convert nitrate to nitric oxide at a Cu-(II) center under mild conditions.The beta-diketiminato complex [Cl2NNF6]-Cu-(kappa(2)-O2NO) engages in O-atom transfer with variousthiols (RSH) to form the corresponding copper-(II) nitrite [Cu-II]-(kappa(2)-O2N) and sulfenic acid (RSOH).The copper-(II) nitrite further reacts with RSH to give S-nitrosothiols RSNO and [Cu-II](2)(mu-OH)(2) en route to NO formation via [Cu-II]-SR intermediates. The gasotransmitter H2S also reducesnitrate at copper-(II) to generate NO, providing a lens into NO3 (-)/H2S crosstalk. The interactionof thiols with nitrate at copper-(II) releases a cascade of N- andS-based signaling molecules in biology.

Automated summary

Reduction of nitrate is a challenging chemical task in the environment and biology, but it can be facilitated by thiols, ubiquitous reductants in biology, under mild conditions. Thiols react with nitrate at a Cu-(II) center to convert it into nitric oxide, releasing a cascade of N- and S-based signaling molecules. Additionally, nitrate can be reduced to generate nitric oxide by the gasotransmitter H2S at copper-(II), revealing a crosstalk between nitrate and H2S.