Theoretical study of structures and stability of the hydrogen-bonded complexes between 2-hydroxybenzonitrile (o-cyanophenol) and CO

The structures and stability of the hydrogen-bonded complexes between o-cyanophenol and CO: (syn) o-CNPhOH⋯CO (syn) o-CNPhOH⋯OC (anti) o-CNPhOH⋯CO and (anti) o-CNPhOH⋯OC have been investigated employing ab initio and DFT calculations at different basis sets. Full geometry optimisation was made for the complexes studied. The nature of the hydrogen bonding in the complexes and the influence of CO on the properties of o-cyanophenol has been investigated. The corrected values of the dissociation energy for each hydrogen-bonded complex have been calculated in order to estimate the strength of the hydrogen bonds. Having in mind the corrected values of the dissociation energy, the studied hydrogen-bonded complexes can be ordered according their stability as follows: (anti) o-CNPhOH⋯CO>(syn) o-CNPhOH⋯CO>(anti) o-CNPhOH⋯OC>(syn) o-CNPhOH⋯OC. The hydrogen bonding between o-cyanophenol and CO leads to changes in the geometrical parameters (bond lengths and angles) of the monomers. These changes depend on the strength of the hydrogen bonds. It was established that the hydrogen bonding leads to a charge rearrangement in the monomers. The most sensitive to the complexation are the atoms, taking part in the hydrogen bonding.