An investigation of the co-ordination properties of (2,3,7,8,12,13,17,18-octamethylcorrolato)iron(III) by nuclear magnetic resonance spectroscopy

Abstract

The reactivity of (2,3,7,8,12,13,17,18-octamethylcorrolato)iron(III) towards axial ligands such as pyridine, chloride and isocyanide has been studied by means of optical and ¹H NMR spectroscopy. Relaxation rate measurements and analysis of the temperature dependence of the isotropic shifts are indicative of an S=½ spin state for the complex in chloroform solution, whilst its pyridine adduct exhibits a mixed spin state for the metal atom. The existence in chloroform solution of two different species related to a chloride binding equilibrium has been demonstrated by a saturation transfer experiment. Both ¹H NMR and electronic spectra of the complex are indicative of the formation of molecular complexes between different macrocyclic rings competing with axial ligation.