Bonding studies from charge-transfer absorption and magnetic circular dichroism spectra. Part II. The complex hexacyanoferrate(III) and pentacyanoferrate(III) complexes of C4v, symmetry
Abstract
Magnetic circular dichroism (m.c.d.) and absorption spectra of the hexacyanoferrate (III) ion have been measured in two host lattices at room and liquid-helium temperatures. Previous interprepations of the charge-transfer(c.t)bands have been confirmed and new assignments of the d-d transitions have been made. With the complexes [Fe(Cn)5L]n–(L = NH3, H2O, PPh3, SCN–, or N3–) a new band has been detected, the energy of which is very sensitive to the nature of the ligand L. This band is assigned as L → Fe charge transfer and band energies follow the pattern previously observed in substituted halogeno-complexes of IrVI; namely, a particular high-energy filled molecular orbital with PPh3 moves to lower energy with the ligands H2O and NH3. The aqopentacyano-ferrate(III) complex shows indications of dimer formation in solution.