A computational study of dimers and trimers of nitrosyl hydride: Blue shift of NH bonds that are involved in H-bond and orthogonal interactions

Ab initio calculations at MP2/aug-cc-pVTZ level were used to analyze the interactions between nitrosyl hydride (HNO) dimers and trimers. The structures obtained have been analyzed with the Atoms in Molecules (AIMs) and Natural Bond Orbital (NBO) methodologies. Four minima were located on the potential energy surface of the dimers. Nine different structures have been obtained for the trimers. Three types of interactions are observed, NH⋯N and NH⋯O hydrogen bonds and orthogonal interaction between the lone pair of the oxygen with the electron-deficient region of the nitrogen atom. Stabilization energies of dimers and trimers including BSSE and ZPE are in the range 4-8 kJ mol−1 and 12-19 kJ mol−1, respectively. Blue shift of NH bond upon complex formation in the ranges between 30-80 and 14,114 cm−1 is predicted for dimers and trimers, respectively.