Acid-induced reduction of nitrites(NO_(2)-)to nitric oxide(NO)at Cu/Fe centers is one of the key steps in the nitrogen cycle and serves as an essential path to NO generation.In this study,we report the acid-catalysed ...Acid-induced reduction of nitrites(NO_(2)-)to nitric oxide(NO)at Cu/Fe centers is one of the key steps in the nitrogen cycle and serves as an essential path to NO generation.In this study,we report the acid-catalysed conversion of NO_(2)-to NO at the Cu^(II)centers in Cu^(II)-nitrito complexes,[(Me_(2)BPMEN)Cu^(II)(NO_(2)-)]+(1)and[(H_(2)BPMEN)Cu^(II)(NO_(2)-)]+(2).Both the Cu^(II)-NO_(2)-complexes showed the formation of NO(g)along with H_(2)O_(2)when reacted with one equivalent acid(H6^(+))via the N-O bond homolysis of the presumed Cu^(II)-nitrous acid([Cu-ONOH]^(2+))intermediate.However,the H_(2)O_(2)amount decreased with time or an increase in H6^(+)and completely disappeared when H6^(+)was more than about two equivalents accompanied by the generation of H_(2)O.We detected the released NO(g)by using headspace gas chromatography/mass spectrometry;moreover,the NO(g)evolution was confirmed by the formation of a significant amount of{CoNO}^(8),[(12-TMC)Co(NO)]^(2+)up to(90±5%)in the above reactions.Mechanistic investigations using^(15)N-labeled-^(15)NO_(2)-and^(18)O-labeled-^(16)O^(14)N^(18)O-revealed that the N-atom in NO is derived from the^(18)ONO-ligand,which was further confirmed by the detection of^(15)NO and N^(18)O gas in headspace gas chromatography/mass spectrometry.We also monitored and characterized the formation of H_(2)O_(2)(one equivalent of H6^(+))and H_(2)O(two equivalents of H6^(+))and the results describe the rationale behind biological NO_(2)-reduction reactions generating NO along with H_(2)O.We observed more than 90%recovery of(1)after 10 catalytic cycles of NO(g)generation.展开更多
基金supported by Grants-in-Aid(CRG/2021/003371)from SERB-DST.P.B.Kulbir,thank IISER Tirupati for their fellowship.
文摘Acid-induced reduction of nitrites(NO_(2)-)to nitric oxide(NO)at Cu/Fe centers is one of the key steps in the nitrogen cycle and serves as an essential path to NO generation.In this study,we report the acid-catalysed conversion of NO_(2)-to NO at the Cu^(II)centers in Cu^(II)-nitrito complexes,[(Me_(2)BPMEN)Cu^(II)(NO_(2)-)]+(1)and[(H_(2)BPMEN)Cu^(II)(NO_(2)-)]+(2).Both the Cu^(II)-NO_(2)-complexes showed the formation of NO(g)along with H_(2)O_(2)when reacted with one equivalent acid(H6^(+))via the N-O bond homolysis of the presumed Cu^(II)-nitrous acid([Cu-ONOH]^(2+))intermediate.However,the H_(2)O_(2)amount decreased with time or an increase in H6^(+)and completely disappeared when H6^(+)was more than about two equivalents accompanied by the generation of H_(2)O.We detected the released NO(g)by using headspace gas chromatography/mass spectrometry;moreover,the NO(g)evolution was confirmed by the formation of a significant amount of{CoNO}^(8),[(12-TMC)Co(NO)]^(2+)up to(90±5%)in the above reactions.Mechanistic investigations using^(15)N-labeled-^(15)NO_(2)-and^(18)O-labeled-^(16)O^(14)N^(18)O-revealed that the N-atom in NO is derived from the^(18)ONO-ligand,which was further confirmed by the detection of^(15)NO and N^(18)O gas in headspace gas chromatography/mass spectrometry.We also monitored and characterized the formation of H_(2)O_(2)(one equivalent of H6^(+))and H_(2)O(two equivalents of H6^(+))and the results describe the rationale behind biological NO_(2)-reduction reactions generating NO along with H_(2)O.We observed more than 90%recovery of(1)after 10 catalytic cycles of NO(g)generation.
