Vibrational spectroscopic investigations and density functional theory calculations on trans-diaquabis(picolinato)zinc(II) dihydrate complex

Abstract

FT-Raman and FT-infrared spectra of pyridine-2-carboxylic acid (picolinic acid) and its corresponding trans-diaquabis(picolinato)zinc(II) dihydrate complex were recorded. Density functional theory was used in order to calculate the optimized geometries and harmonic vibrational wavenumbers of the coordination compound and its isolated ligand. The calculation for the complex was performed under Ci symmetry constraints and all 93 vibrational modes were classified as either Raman active (ag symmetry) or infrared active (au symmetry). The assignment of the characteristic bands was performed by using the calculated harmonic wavenumbers and their Raman intensities. The agreement between the calculated and experimental values of both the structural parameters and the vibrational modes was fairly good. The influence of metal coordination on the picolinic acid was monitored by the wavenumber shift of certain marker bands and the appearance of new vibrational bands. Copyright © 2003 John Wiley & Sons, Ltd.