Catalytic disproportionation of N-alkylhydroxylamines bound to pentacyanoferrates

Abstract

The substituted hydroxylamines, CH₃N(H)OH (N-methylhydroxylamine) and (CH₃)₂NOH (N,N-dimethylhydroxylamine), disproportionate catalytically to the corresponding alkylamines and oxidation products, only in the presence of [Fe(CN)₅H₂O]³⁻. Substitution kinetic measurements suggest an initial coordination step to Fe(II). Two parallel N- and O-coordination modes are considered with the subsequent formation of Fe(III), free aminyl (RNCH₃) and nitroxide (RN(CH₃)O) radicals (R = H, CH₃). With CH₃N(H)OH, bound nitrosomethane, CH₃NO, has been characterized by UV-visible and IR spectroscopies. The mechanism is discussed on the basis of common and differential features with respect to the disproportionation of hydroxylamine catalyzed by the same Fe-fragment.