Ferric complexes of nitrogen-containing heterocyclic ligands; their electron paramagnetic resonance and vibrational spectra

Abstract

The complexes Fe(pyrazole)₃Cl₃, Fe(3-methylpyrazole)₃Cl₃, Fe(py)₄Cl₃, Fe(pyrimidine)₂Cl₃, and Fe(pyrazine)_5/2Cl₃ have been prepared; the vibrational spectra of these and a number of similar, indium complexes have been recorded and metal–nitrogen and metal–halogen vibrational modes assigned. The e.p.r. spectra of some of the complexes are discussed and the results compared with the predictions of the vibrational spectra. The co-ordinating ability of a number of ligands is rationalised in terms of pK_a and steric effects.