BROWNS BOND VALENCES, A MEASURE OF THE STRENGTH OF HYDROGEN-BONDS

The intramolecular bond valences SOH Of water molecules in condensed m aterials, which cannot be calculated with sufficient accuracy from exp erimental O-H bond lengths, have been determined indirectly from the i ntermolecular H...O distances using the equations s = 1 - Sigma s(H... O) and s' = s(O-H)/(s(O-H) + Sigma s(H...O)) The bond valences s and s ' thus obtained correlate almost linearly with the wavenumbers of the respective OD stretching modes of matrix isolated HDO molecules (slope s 2.79 x 10(-4) and 2.83 x 10(-4) v.u. cm, origins 1.79 x 10(-1) and 1 .72 x 10(-1) v.u., respectively; v.u. = valence units). The bond valen ces and correlation curves established, which can be, used for assigni ng hydrogen bonds even in the presence of multifurcated bonds, are dis cussed with respect to the physical reliability of s and s', the possi ble correction and improvement of inaccurate experimental O-H distance s via the respective bond valences, and the significance bf the direct proportionality of the bond valences to the wavenumbers of the stretc hes.