LATTICE VIBRATION-SPECTRA .89. NEAR-INFRARED SPECTRA OF M(OH)CL (M=CA, CD, SR), ZN(OH)F, GAMMA-CD(OH)(2), SR(OH)(2), AND BRUCITE-TYPE HYDROXIDES M(OH)(2) (M=MG, CA, MN, FE, CO, NI, CD)

Near-infrared (NIR) spectra of Zn(OH)F, gamma-Cd(OH)(2), Sr(OH)(2), th e isostructural M(OH)Cl (M = Ca, Cd, Sr), and the brucite-type hydroxi des M(OH)(2) (M = Mg, Ca, Mn, Fe, Co, Ni, Cd) (as well as of deuterate d and isotopically-diluted specimens) are recorded and assigned to ove rtones and combination bands of the stretching modes. The anharmonicit ies obtained are compared with those calculated by approximation proce dures. The anharmonicities increase with both increasing strength of h ydrogen bonds and decreasing M-O distances in the case of non-hydrogen -bonded OH- ions. The intensities of the respective NIR bands decrease with the increase in strength of hydrogen bonds. In the case of centr osymmetric brucite-type hydroxides, of which direct overtones are infr ared-forbidden, the bands observed in the NIR region behave like overt ones of uncoupled stretching modes.