INTERPRETATION OF THE VIBRATIONAL-SPECTRA OF CHLORAMIDE, H2NCL, ON THE BASIS OF POST-HARTREE-FOCK FORCE-FIELD

The ab initio RHF and MP2 force fields were calculated for chloramide with the use of the 6-31G, 6-31G** and 6-311G** basis sets. The ab in itio force fields obtained were scaled by fitting to the available exp erimental vibrational frequencies for the H2NCl, (H2NCl)-Cl-37 and HDN Cl species. This makes it possible to extend the set of transferable s cale factors we recommended earlier. Minimal differences were observed between the scaled MP2 and RHF force fields, although the inclusion o f electron correlation improved the ab initio data and showed better a greement with the observed frequencies obtained by scaling. The effect produced by empirical anharmonicity corrections to the observed NH(ND ) stretching frequencies on the results of the fitting was tested. The experimentally observed satellite band at 1032 cm(-1) in the infrared spectrum of the parent substance was identified, and it was attribute d to the presence of HNCl2 in the sample, in contrast to previous assi gnments to vibrations of H2NCl or any of its isotopomers. (C) 1997 Els evier Science B.V.