Quantum-chemical theoretical study of blue-shifting hydrogen bonding complexes between CHF3 and SO2, CO2, CO in the gas phase

Abstract

All calculations were performed at the different high level of theory by using both the two methods MP2, B3LYP and the basis sets 6-31+G(d.p), 6-31++G(2d.2p). The interaction energies are corrected with ZPE and BSSE, about -0.16 and -1.40 kcal.mol^-1. The blue-shifts have obtained in all the examined complexes. The electric field of the H-acceptor is the fundamental condition for the blue-shifting hydrogen bond. The C-H bond length upon complex formation is controlled by a balance of two main factors acting in opposite directions. This is rehybridization of C atom and strongly hyperconjugative interaction in complex. The NBO analysis indicates that the H-index is not major reason for physical origin of improper blue-shifting hydrogen bond but the EDT is also reason for the contraction. The R_E energy index is also a discriminative factor for the blue-shift and the red-shift in the stretching frequency.