Iron(III) hetero-ligand complexes containing 1,10-phenanthroline derivatives, chloride and dimethyl sulfoxide: synthesis, characterization, crystal structure determination and luminescent properties

[Fe(Me-phen)Cl-4][Me-phen center dot H] (1) and [Fe(Cl-phen)Cl-4][Cl-phen center dot H] (2) complexes were prepared from the reactions of FeCl3 center dot 6H(2)O with 5-methyl-1,10-phenanthroline (Me-phen) and 5-chloro-1,10-phenanthroline (Cl-phen), respectively, in a 0.1 M aqueous solution of HCl. Stepwise addition of dimethyl sulfoxide to the solution of 1 in methanol results in a mixed ligand complex, [Fe(Me-phen)Cl-3(DMSO)] (3). Complex 3 was also prepared by two other methods. The reaction of a methanol solution of [Fe(Me-phen)Cl-4][Me-phen center dot H] (1) with [Fe(DMSO)(4)Cl-2][FeCl4] in 1:6 ratio led to 3. Complex 3 was also prepared from the reaction of 5-methyl-1,10-phenanthroline with [Fe(DMSO)(4)Cl-2][FeCl4] in 1:1 ratio in methanol. The three complexes were characterized by IR, UV-Vis, H-1 NMR and luminescence spectroscopy and their structures were studied by the single-crystal diffraction method. Calculation methods were employed to study the isomerization of (3) in solution.