Lewis acid–Lewis base interactions: From NFH3+⋯NCH and NF4+⋯NCH complexes to NFH3+⋯(NCH)n and NF4+⋯(NCH)n clusters

The Lewis acid centers of NFH3+ and NF4+ were analyzed and the MP2/6-311++G(d,p) calculations were performed for complexes of these cations with HCN molecule. The HCN molecule may be linked through the N-atom with the H, F or N centre of cation, i.e. through the hydrogen bond or the σ-hole bond. The geometry optimizations were also performed for the NFH3+⋯(NCH)n and NF4+⋯(NCH)n clusters (n up to 8). The Quantum Theory of Atoms in Molecules and the Natural Bond Orbitals method were applied to analyze mechanisms of the formation of intermolecular links. The DFT/NEDA decomposition scheme was used and it was found that for the hydrogen bonded systems the charge transfer is the most important attractive interaction while for the N⋯N and N⋯F σ-hole bonds it is the electrostatic interaction followed by the polarization.