Nitric oxide (NO) plays numerous, disparate biological roles which range from signaling in the respiratory system to vasodilation in the cardiovascular system to host defense against microbial pathogens. Nonetheless, the discrete molecular mechanisms involved in NO processing are not well understood: its molecular relatives S-nitrosothiols (RSNOs) and nitrite (NO2-) can also serve as reservoirs of NO-like behavior. Thus, an understanding of the discrete mechanistic pathways by which NO, RSNOs, and NO2- form, interconvert, and react with molecular targets of biological relevance is crucial in understanding the molecular basis for physiological effects ascribed to NO and its molecular relatives. Employing a family of biologically relevant copper nitrite complexes [CuII](κ2-O2N), we examine the reactivity of copper-bound nitrite with thiols RSH, amines R2NH, and alcohols ROH. Nitrosation occurs via the highly electrophilic nitrite to provide organonitroso species RS-NO, R2N-NO, and RO-NO. Moreover, facile reaction between RSNO species and either [CuI] or [CuII]-SR intermediates provide low barrier pathways for NO formation. Curiously, phenols ArOH react with [CuII](κ2-O2N) via proton-coupled electron transfer, reducing copper-bound NO2- to NO with formation of phenoxy radicals ArO● and [CuII]-OH species. Detailed studies outline this novel H-atom transfer pathway for NO generation enabled by nitrite coordination at electrophilic copper(II) sites.

Modeling nitric oxide signaling chemistry via nitrite at copper sites

254th National Meeting (2017)

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