Chapter 5 - Structural Chemistry of Lanthanide Complexes

Abstract

This chapter discusses the structural chemistry of lanthanide complexes including their complex formation and coordination number. These factors for rare earth ions are different from those of transition metals. The chemical composition of rare earth complexes cannot by itself reveal the coordination number of the central metal ion. There are many complexes containing hydrated water molecules and coordinated water molecules. The coordination number can sometimes be established by coordinated physical measurements such as conductance, molecular weight measurement, infrared, UV–VIS–near IR, and emission spectroscopy. The coordination numbers of solid complexes can be obtained by X-ray diffraction methods. Infrared spectroscopy and the conductance methods were used in the determination of the coordination numbers of Nd(N03)3.4DMSO and Dy(N03)3.3DMSO complexes. Coordination numbers of complexes in solution are more difficult to determine and are usually inferred from spectroscopic and conductance data. The existence of rare earth complexes with larger coordination numbers is due to the large size of rare earth ions and the predominant ionic nature of the bond.