Harmonic vibrational blue shifts in FXeH…Y complexes (Y = N2, CO, BF and HF) predicted by a perturbative model

The Xe-H and F-Xe bond-length change and the harmonic vibrational frequency shift of the Xe-H and F-Xe stretching vibration of FXeH on formation of the linear FXeH…Y (Y = N2, CO, BF) complexes and the non-linear FXeH…FH and FH…FXeH complexes were determined by ab initio computations at the MP2/6-311++G(2d, 2p)/LJ 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 Xe-H (F-Xe) bond length from its equilibrium value in the isolated FXeH monomer. Blue shifts of the Xe-H stretch were obtained for all of the complexes, except for FXeH…BF, and these results are rationalized using the model.