Solvent-dependent 2H nuclear magnetic resonance spectra and solvatochromism in ligand-field absorption bands of cis-[CrF2N4]-type complexes with triethylenetetramine, pyridine or 2,2′-bipyridine

Abstract

The solvent-dependent ²H NMR spectra and solvatochromism in ligand-field absorption bands of cis-[CrF₂N₄]-type complexes with deuteriated triethylenetetramine (trien), pyridine (py) and 2,2′-bipyridine (bipy) have been used to demonstrate the sensitivity of the angular overlap model parameters to the solvent co-ordination sphere, as has also been observed for trans-[CrF₂([²H₄]dadad)]⁺(dadad = 1,10-diamino-4,7-diazadecane). The cis effect was found to account reasonably well for the solvent dependence of the spectra for both the cis and trans complexes. The inverse correlation of the ²H NMR chemical shifts for the β- and γ-deuterons in the py complexes and 4- and 5-deuterons in the bipy complexes with the solvent electron acceptor number gave direct evidence for the π-acceptor bond properties of aromatic heterocyclic ligands in the complexes.