MATRIX INFRARED-SPECTRA AND AB-INITIO CALCULATIONS OF THE NITROUS-ACID COMPLEXES WITH N-2 AND CO

The complexes formed by trans- and cis-HONO isomers with nitrogen and carbon monoxide have been observed and characterized in argon matrices . Six perturbed trans-HONO vibrations and four perturbed cis-HONO vibr ations were identified for both the N-2 and CO complexes. The perturba tion of the OH group vibrations proves that all four complexes are hyd rogen banded; the blue shifts of the CO vibrations in trans- and cis-H ONO complexes as compared to CO monomer indicate the OC ... HONO struc tures in which carbon atoms are the acceptor sites. The strength of in teraction, as evidenced by the perturbation of the OH vibrational mode s of the nitrous acid, increases from cis- to trans-isomer and from ni trogen to carbon monoxide. Theoretical studies of the structure and sp ectral characteristics of the complexes formed between the two isomers of nitrous acid and nitrogen or carbon monoxide were carried out on t he electron correlation level with the 6-31G(d,p) basis set. The bindi ng energy and the calculated spectral parameters are in very good agre ement with experimental data.