Conversion of Nitric Oxide into Nitrous Oxide as Triggered by the Polarization of Coordinated NO by Hydrogen Bonding.

Abstract

Reduction of the {Co(NO)}(8) cobalt-nitrosyl N-confused porphyrin (NCP) [Co(CTPPMe)(NO)] (1) produced electron-rich {Co(NO)}(9) [Co(CTPPMe)(NO)][Co(Cp*)2 ] (2), which was necessary for NO-to-N2 O conversion. Complex 2 was NO-reduction-silent in neat THF, but was partially activated to a hydrogen-bonded species 2⋅⋅⋅MeOH in THF/MeOH (1:1, v/v). This species coupling with 2 transformed NO into N2 O, which was fragmented from an [N2 O2 ]-bridging intermediate. An intense IR peak at 1622 cm(-1) was ascribed to ν(NO) in an [N2 O2 ]-containing intermediate. Time-course ESI(-) mass spectra supported the presence of the dimeric [Co(NCP)]2 (N2 O2 ) intermediate. Five complete NO-to-N2 O conversion cycles were possible without significant decay in the amount of N2 O produced.