The F19–H1 coupling constants transmitted through covalent, hydrogen bond, and van der Waals interactions

Abstract

The F19–H1 coupling constants were calculated on the multiconfiguration self-consistent field (MCSCF) level in several systems, ranging from covalently bonded HF, hydrogen bonded FHF− and (HF)2 complexes to weak van der Waals complex CH4–HF. The sign of the F19–H1 coupling varies in this sequence, and its absolute value decreases. Still, it is sizable even for CH4–HF. The distance dependence of F19–H1 coupling is essentially the same in all systems under study, and the calculations for FHF− with distorted geometry suggest that the value of F19–H1 coupling is determined mainly by molecular geometry. F19–F19 coupling constants were also analyzed. F19–F19 intermolecular coupling in (HF)2 is substantial but has the opposite sign to that in FHF− and its counterpart in (H2O)2.