Copper(I)/NO Reductive Coupling Producing a trans-Hyponitrite Bridged Dicopper(II) Complex: Redox Reversal Giving Copper(I)/NO Disproportionation.

A copper complex, [Cu(tmpa)(MeCN)], effectively reductively couples NO at RT in methanol (MeOH), giving a structurally characterized hyponitrito-dicopper(II) adduct. Hydrogen-bonding from MeOH is critical for the hyponitrite complex formation and stabilization. This complex exhibits the reverse redox process in aprotic solvents, giving Cu + NO, leading to Cu-mediated NO-disproportionation. The relationship of this chemistry to biological iron and/or copper mediated NO reductive coupling to give NO is discussed.