Comprehensive ab initio studies of nuclear magnetic resonance shielding and coupling constants in XH⋯O hydrogen-bonded complexes of simple organic molecules

The influence of hydrogen-bond formation on the scalar spin–spin coupling constants and NMR shielding constants in ${\mathrm{CH}}_{\mathrm{2}}{\mathrm{O–H}}_{\mathrm{2}}\mathrm{O},$ ${\mathrm{C}}_{\mathrm{2}}{\mathrm{H}}_{\mathrm{2}}{\mathrm{–H}}_{\mathrm{2}}\mathrm{O},$ ${\mathrm{CH}}_{\mathrm{3}}{\mathrm{OH–H}}_{\mathrm{2}}\mathrm{O},$ and $({\mathrm{HCOOH)}}_{\mathrm{2}}$ complexes has been calculated using correlated MO (MCSCF and MP2) methods. The hydrogen-bond transmitted spin–spin coupling constants are also reported. The iso- and anisotropic ${}^1\mathrm{H}$ shielding constants are found to be the most general parameters of the hydrogen bond. The changes in ${}^1\mathrm{J(}\mathrm{XH})$ coupling in the proton donor also correlate with the XH⋯Y hydrogen bond strength. A similar correlation is found in the intermolecular ${}^{\text{1h}}\mathrm{J(}\mathrm{HY})$ and ${}^{\text{2h}}\mathrm{J(}\mathrm{XY})$ couplings. These couplings are substantial and dominated by the Fermi-contact term in contrast to the longer-range hydrogen-bond transmitted couplings where the noncontact terms prevail.