On the competition between weak O H⋯F and C H⋯F hydrogen bonds, in cooperation with C H⋯O contacts, in the difluoromethane – tert -butyl alcohol cluster

The 1:1 complex of tert-butyl alcohol with difluoromethane has been characterized by means of a joint experimental-computational investigation. Its rotational spectrum has been recorded by using a pulsed-jet Fourier-Transform microwave spectrometer. The experimental work has been guided and supported by accurate quantum-chemical calculations. In particular, the computed potential energy landscape pointed out the formation of three stable isomers. However, the very low interconversion barriers explain why only one isomer, showing one O. H⋯F and two C. H⋯O weak hydrogen bonds, has been experimentally characterized. The effect of the H. →. tert-butyl-group substitution has been analyzed from the comparison to the difluoromethane-water adduct.