WEAK C-H ... O INTERACTIONS AND H_(2)O INTERNAL ROTATION IN THE HCClF_(2)-H_(2)O AND HCBrF_(2)-H_(2)O DIMERS

摘要

The polarity of the C-H bond involved in a weak C-H... X interaction may be tuned by introducing different combinations of halogen substituents on the carbon atom. In this study, the structures of the HCClF_(2)-H_(2)O and HCBrF_(2)-H_(2)O dimers have been studied by rotational spectroscopy and theoretical methods, with the hope of observing weak C-H...O interactions. Ab initio calculations (MP2/6-311++G(2d,2p)) predict cyclic structures for both dimers, with a C-H...O and an O-H...X (X velence Cl or Br) interaction present in each complex. Fourier-transform microwave spectroscopic investigations of both species have confirmed that this structural motif is present, although the experimental results display some significant differences from the theoretical predictions.