Blue shifting and red shifting hydrogen bonds: A study of the HArF⋯N2 and HArF⋯P2 complexes

Abstract

An ab initio computational study of the properties of two weakly bound linear complexes formed between the recently discovered argon-containing compound HArF and the homonuclear diatomic molecules N₂ and P₂ was undertaken at the MP2/6-311++G(2d,2p) level of theory. The complex N₂⋯HArF was found to have a binding energy of 912 cm⁻¹ with respect to the monomer subunits, while the other complex P₂⋯HArF was found to have a binding energy of 1130 cm⁻¹. The N₂⋯HArF complex exhibits a large harmonic vibrational frequency blue shift of 153 cm⁻¹ for the Ar–H stretching vibration mode, while P₂⋯HArF exhibits a large red shift of 116 cm⁻¹ for the same vibrational mode; in both complexes the IR intensity of the Ar–H stretching vibration decreases on complexation. In this study we attempt to explain these frequency shifts.