M. Alcami et al., Exploring the potential energy surface of the association of Cu+ to oxaziridine, nitrosomethane, and formaldoxime, J PHYS CH A, 102(49), 1998, pp. 10120-10127
The catalytic role of Cu+ on the isomerization processes among oxaziridine
and its isomers methylenimine N-oxide, nitrosomethane, and formaldoxime has
been investigated by studying the corresponding potential energy surfaces
through the use of high-level DFT calculations. The geometries of the diffe
rent stationary points were optimized at the B3LYP/6-311G(d,p) level while
the final energies were obtained using a 6-311+G(2df,2p) basis set expansio
n. Our results show that oxaziridine, contrary to what has been found for f
ormamide, behaves as a nitrogen base when the reference acid is Cu+, since
the oxygen-attached species is predicted to be 9.2 kcal/mol less stable tha
n the nitrogen-attached structure. Both nitrosomethane and formaldoxime are
also predicted to be nitrogen bases in gas-phase reactions with Cu+, while
for methylenimine N-oxide only the oxygen and the carbon-attached complexe
s were found to be minima of the potential energy surface, the former being
almost 21 kcal/mol more stable than the latter. Among the cationized speci
es the most stable corresponds to the attachment of the metal cation to the
nitrogen atom of formaldoxime, which is also the most stable neutral. Howe
ver, the energy gaps found for the neutral species differ significantly fro
m those found for the corresponding Cu+ complexes. Cu+ association to oxazi
ridine catalyzes the C-O bond fission, favoring the formation of an open H2
C-NH-OCu+ complex. The isomerization processes leading from nitrosomethane
to formaldoxime and to methylenimine N-oxide as well as that connecting the
latter two compounds are also catalyzed by Cu+ association in the gas phas
e.