Raman spectra of Cu(HCO2)2 · 4H2O in the region of OH stretches at room temperature

Abstract

AbstractPolarized Raman spectra of Cu(HCO2)2 · 4H2O (CFT) and 5% deuterated CFT were observed at room temperature in the region of the OH and the decoupled OD stretches, respectively. The analysis of the decoupled OD stretches clarified the wavenumbers for seven OD sites in the two‐dimensionally hydrogen‐bonded network. In the polarized Raman spectra of CFT it was found that the polarized spectra parallel and perpendicular to the six‐membered hydrogen‐bonded ring differ greatly; the parallel spectrum corresponds well to that the ice Ih. The strong band in the perpendicular spectrum is explained in terms of the uncoupled stretches due to the OH groups which do not participate in the six‐membered ring. These spectra were analysed using 72 water molecules with disorder to the hydrogen positions which satisfy a periodic boundary condition. It was found that the observed Raman spectra are approximately explained in terms of the initial set of force constants. The Raman spectrum of deuterated CFT in the polycrystalline state could also be simulated well.