WATER-MOLECULES AND HYDROXIDE IONS IN CONDENSED MATERIALS - CORRELATION OF SPECTROSCOPIC AND STRUCTURAL DATA

The main criteria used to determine the strengths of hydrogen bonds O- H ... O formed in solid materials are the respective intermolecular bo nd distances and the wavenumbers of the OH(D) stretching modes observe d in the infrared and Raman spectra including their temperature and pr essure evolution. The intramolecular O-H(D) bond lengths, however, are too inaccurate, by at least one order of magnitude, to provide quanti tative information, even if neutron diffraction data are available. Th is problem, however, has been overcome by improvement of the experimen tal data via the additivity of the bond valences of the intramolecular O-H(D) and intermolecular H(D)... O bonds (Lutz et al., J. Mel. Struc t., 351 (1995) 205). Such corrected internal O-H(D) hydrogen bond leng ths, which are a powerful measure of the hydrogen-bond strength, corre late nearly linearly with the wavenumbers of the OD stretching modes o f isotopically dilute samples (matrix-isolated HDO molecules). The v(O D) vs. r(O-H(D)) correlation curve (slope, -1.19 x 10(-2) pm cm; origi n, 126.0 pm; r.m.s. dev., 38 cm(-1)) thus established for the first ti me can be used to determine the O-H(D) bond lengths of H2O molecules i n solid hydrates from infrared and Raman spectroscopic data. (C) 1997 Elsevier Science B.V.