d-f Metal Ion Interaction through Fe-C≡N-Ln Bridge between Dicyanobis(1,10-phenanthroline)iron(II) Complex and LnCl3

By adding lanthanoid ion (Ln) to a solution of non-charged iron(II) complex, [Fe(CN)2(phen)2], the blue shift in MLCT band of the Fe(II) complex was observed in ethanol, but was not in DMSO. The extent of the band shift depends on the lanthanoid ion size, which is explained by means of Fe-C≡N-Ln interaction. In DMSO, however, the lanthanoid ion is solvated too strongly to form the Fe-C≡N-Ln bridging. The existence of the bridging mode was confirmed by means of the crystal analysis for a Fe2Yb2 tetranuclear complex.