Kinetics and mechanism of the reduction of hydroxylamine-O-sulfonic acid by the hexaaquochromium(II) ion

Bakač, Andreja; Simunic, Joan L.; Espenson, James H.

doi:10.1021/ic00330a036

Cited by 3 publications

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“…NH 2 OH to NH 3 by several reductants has been recognized. 1a Formation of Cr III NH 3 3+ in the reaction of aqueous Cr(II) with hydroxylamine-O-sulfonic acid 40 provides additional support on the coordination of NH 2 OCH 3 to Fe(II) through the N atom in eq 3, with subsequent oxidation to Fe(III), eq 5. We found no evidence on the direct oxidation of [Fe II (CN) 5 H 2 O] 3À by CH 3 O • .…”

Section: Articlementioning

confidence: 94%

Disproportionation of O-Methylhydroxylamine Catalyzed by Aquapentacyanoferrate(II)

2011

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The aquapentacyanoferrate(II) ion, [Fe(II)(CN)(5)H(2)O](3-), catalyzes the disproportionation reaction of O-methylhydroxylamine, NH(2)OCH(3), with stoichiometry 3NH(2)OCH(3) → NH(3) + N(2) + 3CH(3)OH. Kinetic and spectroscopic evidence support an initial N coordination of NH(2)OCH(3) to [Fe(II)(CN)(5)H(2)O](3-) followed by a homolytic scission leading to radicals [Fe(II)(CN)(5)(•)NH(2)](3-) (a precursor of Fe(III) centers and bound NH(3)) and free methoxyl, CH(3)O(•), thus establishing a radical path leading to N-methoxyamino ((•)NHOCH(3)) and 1,2-dimethoxyhydrazine, (NHOCH(3))(2). The latter species is moderately stable and proposed to be the precursor of N(2) and most of the generated CH(3)OH. Intermediate [Fe(III)(CN)(5)L](2-) complexes (L = NH(3), H(2)O) form dinuclear cyano-bridged mixed-valent species, affording a catalytic substitution of the L ligands promoted by [Fe(II)(CN)(5)L](3-). Free or bound NH(2)OCH(3) may act as reductants of [Fe(III)(CN)(5)L](2-), thus regenerating active sites. At increasing concentrations of NH(2)OCH(3) a coordinated diazene species emerges, [Fe(II)(CN)(5)N(2)H(2)](3-), which is consumed by the oxidizing CH(3)O(•), giving N(2) and CH(3)OH. Another side reaction forms [Fe(II)(CN)(5)N(O)CH(3)](3-), an intermediate containing the nitrosomethane ligand, which is further oxidized to the nitroprusside ion, [Fe(II)(CN)(5)NO](2-). The latter is a final oxidation product with a significant conversion of the initial [Fe(II)(CN)(5)H(2)O](3-) complex. The side reaction partially blocks the Fe(II)-aqua active site, though complete inhibition is not achieved because the radical path evolves faster than the formation rates of the Fe(II)-NO(+) bonds.

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Section: Articlementioning

confidence: 94%