NIR-FT RAMAN-SPECTROSCOPIC STUDIES OF HEXAMINE AND PENTAMMINE CHROMIUM(III) COMPLEXES

The NIR-FT-Raman spectra are presented for the hexammine [Cr(NH3)6]X3 (where X = Br-, NO3-), pentamminechloro [Cr(NH3)5Cl]X2 (where X = Cl-, ClO4-), and pentammineaqua [Cr(NH3)5(H2O)]X3 (where X = ClO4-, CF3SO3-) chromium(III) complexes. The NIR-FT-Raman spectra, with an excitation wavelength of 1064 nm, were obtained at room temperature without problems from the strongly colored samples, which often cause problems with excitation by lasers in the visible region. All the Raman frequencies observed from the complexes have been assigned to the skeleton vibrational region from 100 to 600 cm-1. The symmetry and the general valence force constants for the bonds chromium(III)-nitrogen, chromium(III)-oxygen and chromium(III)-chloro have been obtained. The nature of the metal-ligand bond between chromium(III) ammine complexes has been compared with recent results obtained for similar cobalt(III) ammine complexes.