A spectroscopic study of bonding and structure in dihalotetrakis(tolyl isocyanide)iron(II) complexes

Abstract

Both cis and trans isomers of dihalotetrakis(tolyl isocyanide)iron(II) complexes were synthesized and characterized. Nuclear magnetic resonance spectroscopy was used primarily for identification and characterization. The infrared spectra were studied in the isocyanide stretching region and the number of and intensities of the observed bands were used to infer structural information, while the measured spectral shifts were used to discuss the changes in the π-accepting abilities of the isocyanides and the correlation with the electronegativities of the halide ligands. The Mössbauer spectra of these complexes are also reported and the partial center shift and partial quadrupole splitting values of the ligands have been derived. The bonding characteristics of both the isocyanides and the halides are discussed in terms of σ and π contributions. The experimental Mössbauer data is correlated to the other spectroscopic data although it appears to be more informative, especially in the case of indicating the halide π-donor capabilities.