Quantum chemical study of the structures, stability and vibrational spectra of the nitrous acid complexes with B2O2 and C2N2 molecules

Ab initio calculations at the SCF and MP2 levels with 6-311G basis set have been used to investigate the structures, stability and vibrational spectra of the binary complexes B 2 O 2 -HONO(trans) and B 2 O 2 -HONO(cis) alongwith complexes of C 2 N 2 -HONO(trans) and C 2 N 2 -HONO(cis). Full geometry optimization was made for the compl exes studied here. It was established that the complexes B 2 O 2 -HONO(trans) is more stable by 2.40 kcal/mol than the complex B 2 O 2 -HONO(cis) and C 2 N 2 -HONO(trans) is more stable by 2.48 kcal/mol than C 2 N 2 -HONO(cis). The accuracy of the ab initio calculations have been estimated by comparison between the predicted values of the vibrational characteristics (frequencies and infrared intensities) and the available experimental data. It was established that the molecules, used in the present work, are well correlated. The changes in the vibrational frequencies of B 2 O 2 , C 2 N 2 and trans, cis-nitrous acid upon formation of hydrogen bond respectively showed that the complexes B 2 O 2 -HONO(trans) and B 2 O 2 -HONO(cis) have geometry in which the OH group interacts with B 2 O 2 molecules forming a single hydrogen bond. Similar study was also observed for C 2 N 2 and HONO complexes.