Blue-shifted hydrogen-bonded complexes CF3H-(HF)1≤n≤3

The present work demonstrates the existence of cyclic structures in complexes of the CF3H molecule with hydrogen fluoride clusters, (HF)(lless than or equal tonless than or equal to3), due to the formation of two types of hydrogen bonds, C-F...H-F and C-H...F. For the case of n = 3, a significant blue shift of the v(C-H) stretching vibrational mode of fluoroform of about 60 cm(-1) is predicted. This is indeed the largest theoretical estimate of a blue shift in a C-H...X system ever reported in the literature. The present analysis of the geometrical, energetical, and spectroscopic features of the cyclic CF3H-(HF)(1less than or equal tonless than or equal to3) structures shows that the C-F...H-F bond is stronger than the C-H...F interaction. Therefore, they may be referred to as blue-shifted rather than blue-shifting complexes.