Mechanism of pH-dependent decomposition of monoalkylamine diazeniumdiolates to form HNO and NO, deduced from the model compound methylamine diazeniumdiolate, density functional theory, and CBS-QB3 calculations.
Isopropylamine diazeniumdiolate, IPA/NO, the product of the reaction of isopropylamine and nitric oxide, NO, decomposes in a pH-dependent manner to afford nitroxyl, HNO, in the pH range of 13 to above 5, and NO below pH 7. Theoretical studies using B3LYP/6-311+G(d) density functional theory, the polarizable continuum and conductor-like polarizable continuum solvation models, and the high-accuracy CBS-QB3 method on the simplified model compound methylamine diazeniumdiolate predict a mechanism involving HNO production via decomposition of the unstable tautomer MeNN+(O-)NHO-. The production of NO at lower pH is predicted to result from fragmentation of the amide/NO adduct upon protonation of the amine nitrogen.
Dutton
Andrew S
AS
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.
Suhrada
Christopher P
CP
Miranda
Katrina M
KM
Wink
David A
DA
Fukuto
Jon M
JM
Houk
K N
KN
D001372:Aza Compounds / Q000737:chemistry*; D001391:Azo Compounds / Q000737:chemistry*; D004563:Electrochemistry; D006863:Hydrogen-Ion Concentration; D008744:Methylamines / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D009569:Nitric Oxide / Q000737:chemistry*; D009589:Nitrogen Oxides / Q000737:chemistry*; D013816:Thermodynamics
D001372:Aza Compounds; D001391:Azo Compounds; D008744:Methylamines; D009589:Nitrogen Oxides; C452539:diazeniumdiolate; C518951:methylamine diazeniumdiolate; D009569:Nitric Oxide; C039900:nitroxyl