Ab initio calculations and matrix infrared spectra of the nitrous acid complexes with HF and HCl

Abstract

Theoretical studies of the structure and spectral characteristics of the complexes formed by trans- and cis-HONO isomers with hydrogen fluoride and hydrogen chloride were carried out on the electron correlation level with the 6-311++G(2d,2p) basis set. The calculations demonstrate formation of three stable complexes between trans-HONO isomer and HX and five stable complexes between cis-HONO isomer and HX. In the most stable HX···trans-HONO, HX···cis-HONO complexes the HX subunit acts as a proton donor and interacts with an oxygen atom of the OH group which is a proton acceptor. The complexes predicted to be the most stable ones were identified and characterized in argon matrices. Six and five perturbed HONO vibrations of trans-HONO isomer were identified, respectively, for HF···trans-HONO and HCl···trans-HONO complexes whereas two perturbed vibrations of cis-HONO isomer were identified for HF···cis-HONO and HCl···cis-HONO complexes.