Electronic Structure of Tris(1,10-phenanthroline)iron(II) Complex

The SGF MO’s for the π-electron system of 1,10-phenanthroline have been determined by following the Pariser-Parr-Pople’s treatment. For the description of the lower excited states, the configuration interaction among nineteen singly-excited configurations with lower energy has been taken into account. The electronic spectrum of 1,10-phenanthroline has been interpreted on the basis of the results of the theoretical calculation. The SCF MO’s for the π-electron system of a coordinated 1,10-phenanthroline in the tris-iron(II) complex have been determined to be self-consistent under the electrostatic potential field of the central metal ion and the other ligand molecules. On the basis of the results for coordinated ligand, the π-electronic structure of tris-(1,10-phenanthroline)iron(II) ion has been investigated from the theoretical point of view. It has been shown that two kinds of the charge-transfer transitions are responsible for an intense absorption band in the visible region, namely electron transfers from the 3dπ orbital of iron to the lowest and the second lowest vacant π MO’s of the ligand 1,10-phenanthroline. The discussions have been given on the change of the π–π* states of 1,10-phenanthroline by the coordination.