Experimental and theoretical Raman study of the binuclear copper(II) imidazole saccharinato complex

The 1800-180 cm^-1 region of the solid-state Raman spectrum of the binuclear imidazole adduct of copper(II) saccharinate, featuring the shortest C - O bond in all structurally characterized saccharinates, was studied together with those of saccharin and other saccharinato compounds. The appearance of the spectral regions of the characteristic CO, SO₂ and metal-ligand stretching vibrations was correlated with the corresponding structural data. The Raman spectrum of the free saccharinato ion was computed at the HF/6-31++G(d,p) level and used to assign the internal vibrational modes of the saccharinato ligands. It was concluded that, primarily owing to the coupling of the v(CO) mode, two-dimensional d(C - O) vs v[v(CO)] correlations in the metal saccharinates in the solid state are qualitative and more precise analysis should include the effects of other structural factors (e.g. ligation or intermolecular interactions) on the v(CO) wavenumber. Copyright (C) 2000 John Wiley and Sons, Ltd.