The Infrared Spectra of Diaqua Tetra-m - Formato Dichromium (II): A Normal Coordinate Treatment on 1:1 Formate Complex

Abstract

The infrared spectrum of diaqua tetra- m - formato dichromium (II) complex has been obtained in the frequency range 4000 to 400cm-1. A normal coordinate treatment performed on the 1:1 model of the complex gives calculated frequencies in good agreement with the observed ones. In order to assign bands and to see the coupling between various vibrational modes, the potential energy distribution in each normal vibration was calculated with respect to each symmetry coordinate for all the in-plane vibrations. The results show that in spite of the effect of coordination some of the formate ligand based vibrational modes remain localized, though others such as nas(COO) and ds(HCO) couple strongly with ring deformation. The analysis also indicate that bands at 464, 537 and 540 cm-1 are assignable to ns (CrOO) coupled with ring deformation, Cr-Cr mode coupled with ds (Cr-Cr-O) bending and nas (CrOO) coupled with das (C-O-Cr) bending, respectively.

Keywords: Infrared spectrum, normal coordinate treatment, in-plane fundamental vibrations, tetra- m- formato dichromium (II) complex, 1:1 (Cr24+: HCOO-) complex model.


(Global Journal of Pure and Applied Sciences: 2002 9(1): 81-92)