Blue and red shifts in F 3C–H ⋯ B (B = FH, ClH, OH 2, SH 2 and Cl −) complexes predicted by a perturbative model

Abstract

The C–H bond length change and the harmonic vibrational frequency shift of the C–H stretch on formation of the F 3C–H ⋯ B (B = FH, ClH, OH 2, SH 2 and Cl −) complexes were determined by ab initio computations at the MP2/6-311+G(d,p) level of theory. They were found to agree with predictions from perturbation theory involving the first and second derivatives of the interaction energy with respect to displacement of the C–H bond length from its equilibrium value in the isolated F 3C–H monomer. Blue shifts were obtained for all of the complexes, except F 3CH ⋯ Cl − which has a large red shift.