Vibrational study and structure of N-(substituted 5-bromo hydroxyphenylaldiminate) Co(II) complexes

The medium and far IR spectra of the title compounds are discussed and related to the molecular structure. The spectral analysis is supported by a normal coordinate treatment based on a simplified molecular model. Bands near 375 and 290 cm(-1) are assigned to the Co-O and Co-N stretching vibrations, respectively; the corresponding force constants are estimated to be 1.11 and 0.72 mdyn Angstrom(-1). The influence of the N-substitution in the Schiff base ligand on the structure of the bis[(N-R-1-hydroxy-2-phenylaldiminate)5Br]Co(II) complexes, where substituents R are hydrogen, ethyl, butyl, isopropyl, terbutyl, and phenyl, has been studied. Vibrational results indicate a different electronic distribution on the chelate ring for all the complexes. On the basis of these data and that obtained from magnetic susceptibilities and electronic spectroscopy a different geometrical distortion of the coordination sites in the series is inferred.