R. Viswanathan et al., SYNTHESIS, STRUCTURE, SPECTRA AND REDOX CHEMISTRY OF IRON(III) COMPLEXES OF TRIDENTATE PYRIDYL AND BENZIMIDAZOLYL LIGANDS, Journal of the Chemical Society. Dalton transactions, (12), 1996, pp. 2519-2525
A series of high-spin octahedral 1:2 iron(III) complexes of Schiff bas
es derived from salicylaldehyde and aromatic amines and the 1:1 and 1:
2 complexes of bis(pyridin-2-yl)-aza and bis(benzimidazol-2-yl)-aza an
d -thioether ligands have been isolated. The crystal structure of tric
hloro[bis(pyridin-2-ylmethyl)amine]iron(III) has been determined. It c
ontains two crystallographically independent molecules in the asymmetr
ic unit cell. In each molecule iron(III) possesses a rhombically disto
rted octahedral co-ordination, constituted by all the three nitrogens
of the facial ligand and three chloride ions. The effects of stereoche
mical and/or donor atom variations on the UV/VIS and EPR spectra and F
e-III-Fe-II redox potentials and hence on the Lewis acidity of the iro
n(III) centre are discussed. The phenolate-to-iron(III) charge-transfe
r band energy of [FeL(2)(1)]Cl[HL(1) = N-(pyridin-2-ylmethyl)salicylid
eneamine] is higher and its Fe-III-Fe-II redox potential more negative
than those of the corresponding 1:1 complex.