LATTICE VIBRATION-SPECTRA .78. INFRARED AND RAMAN STUDIES ON CALCIUM,ZINC AND CADMIUM HYDROXIDE HALIDES CA(O(H,D))CL, CD(O(H,D))CL, ZN(O(H,D))F AND BETA-ZN(O(H,D))CL

IR and Raman spectra of Zn(OH)F, beta-Zn(OH)Cl and isostructural Ca(OH )Cl and Cd(OH)Cl and of deuterated specimens recorded at ambient and l iquid nitrogen temperature are presented and assigned to OH(OD) stretc hing, librational and translational modes. The spectra obtained are di scussed on the basis of the layered crystal structures of these hydrox ide halides. The main results are (i) detection and proof of the prese nce of very weak hydrogen bonds in the case of M(OH)Cl (M = Ca, Cd) an d for OH(2) of Zn(OH)F [in addition to ordinary hydrogen bonds in the case of beta-Zn(OH)Cl and OH(1) of Zn(OH)F] with OH stretching wavenum bers of the corresponding hydroxide ions partially greater than that o f free, gaseous OH- ions, (ii) a less symmetrical structure of Ca(OH)C l and Cd(OH)Cl compared with that obtained from the heavy atoms alone and (iii) proof of the presence of two different kinds of hydroxide io ns in nearly equal amounts in Zn(OH)F containing two lattice sites eac h occupied by F- and OH-. The high-energy shift of the OH modes mentio ned above is attributed to the synergetic effect.