Anharmonicity of water stretching vibrations in series of isomorphous crystalline hydrates. II. Metal(II) saccharinates hexahydrates (metal(II)∈{Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd})

Abstract

Using three theoretical models, the anharmonicity constants and the harmonic eigenvalues of the O–H and O–D stretching vibrations were calculated for several members of the isomorphous series of metal(II) saccharinates hexahydrates (those of Cr, Mn, Fe, Co, Ni, Cu, Zn and Cd), on the basis of the experimentally obtained (by FTIR spectroscopy) frequencies of isotopically isolated OH and OD species. With a very few exceptions, the anharmonicity of the νOH(OD) vibrations increases with the increase in the hydrogen bond strength. A good correlation was found to exist between the anharmonicity constants and the νOH(OD) frequencies. The positions of the νOH(OD) overtones were estimated using the calculated anharmonicity parameters and the predicted values for the OD oscillators were compared with the experimentally obtained data.