Conformations and charge distributions in fluoronitrosoethylenes and nitrosoethylene

Abstract

The optimized structures, bond orders, and electrostatic potentials for both transoid and cisoid fluoronitrosoethylenes and nitrosoethylene have been calculated by abinitio self-consistent-field molecular orbital procedure. The transoid structures are found to be of lower energy than the cisoids. Analyses of the calculated bond orders show that the C—C bond energy compares well with that of ethylene and the C—N bond energy with that of ethylamine, and therefore the contributions from ionic resonance structures are predicted to be small. The calculated electrostatic potential contour maps show that the presence of the nitroso group completely eliminates the negative potential region associated with the C—C double bond, thus rendering it less susceptible to electrophilic attack. Analyses of the values and relative locations of positive electrostatic potentials correctly predict that the nucleophilic addition to β-carbon is favoured when in the transoid conformation. Keywords: conformation, charge distribution, fluoronitrosoethylenes, nitrosoethylenes.