AB-INITIO STUDY OF THE VARIOUS ISOMERS OF C2H3NO

An ab initio quantum chemical study of the five possible isomers, tran s-and cis-conformations of nitrosoethylene, 4H-1,2-oxazete, 2H-1 aziri ne 1-oxide and acetonitrile oxide, of C2H3NO is reported. Molecular ge ometries and energies have been obtained at the Hartree-Fock and secon d-order Moller-Plesset levels of theory. It is important to note that in both the levels of theory, acetonitrile oxide is found to be the mo st stable isomer among all the five structures. Atomic charges, throug h Mulliken and natural population analysis schemes, dipole moments, en tropies and rotational constants have been calculated using the above- mentioned levels. Various basis sets, 3-21G, 6-31G, 6-31G* and 6-311G , have been used at the HF level of calculation and 6-31G* basis set has been utilized at the MP2 level of calculation. Finally, the vibrat ional spectra of all the five structures have been obtained using the HF/3-21G, HF/6-31G* and HF/6-311G* levels. An imaginary frequency has been found for the cis conformer of the nitrosoethylene molecule at b oth the HF/6-31G* and HF/6-311G* levels. (C) 1998 Elsevier Science B. V.