Crystal structure of brucite-type cobalt hydroxide β-Co{O(H,D)} 2 — neutron diffraction, IR and Raman spectroscopy

Abstract

The crystal structure of brucite-type Co(OD) 2 (space group P3̄ml, Z = 1, a = 317.79(4) pm and c = 464.2(1) pm, R I = 5.89%) has been refined by neutron powder diffraction studies on the basis of 671 observations and 44 reflections. Infrared and Raman spectra of cobalt hydroxide at different degrees of deuteration are presented and assigned to the internal, librational and translational modes. The D⋯O distance of 252.8 pm and the wavenumbers of the OH and OD stretching modes (3604 and 2665 cm −1, 90 K, mean values of the unit-cell group modes) do not exclude the formation of weak trifurcated hydrogen bonds. The librational and translational vibrations of E u species are strongly coupled as shown by the respective isotopic shifts. A reassignment of the IR-allowed librations and lattice vibrations of transition metal brucite-type hydroxides is given.