Collective stabilization through n→π* and P…π phosphorous bonding with cooperative halogen and hydrogen bonding in POCl3-Nitrile dimers: Matrix isolation infrared spectroscopic and ab initio computational studies

Abstract

In the present study, the interaction between phosphoryl chloride (POCl3) with acetonitrile (CH3CN) and benzonitrile (C6H5CN) was explored using matrix isolation infrared spectroscopy and quantum chemical computations. The computations performed at MP2 and B3LYP-GD3 levels of theory with aug-cc-pVDZ basis set indicated the dominant mode of stabilization in POCl3-CH3CN (PACN) dimer is through n→π* (lp(O)…π*(CN)) interaction and for the POCl3-C6H5CN (PBCN) dimer it is predominantly by P…π phosphorous bonding interaction. Computations revealed that the nitrile moiety plays a significant role towards the stability in both the class of dimers. PACN heterodimer appears to be the first prototype, with the -CN moiety playing the acceptor through n→π* charge transfer interaction. The characteristic geometries of the heterodimers stabilized by n→π* and/or P…π interactions have been generated within inert gas matrixes at the cryogenic temperature of 12 K and identified using infrared spectroscopy. The interactions have been comprehensively characterized using quantum theory of atoms in molecules, natural bond orbital analysis, electrostatic potential mapping, energy decomposition and non-covalent interaction analyses.