A series of novel lanthanide polyoxometalates: condensation of building blocks dependent on the nature of rare earth cations

A series of novel lanthanide polyoxomolybdates was synthesized by reaction of lanthanide cations with the Anderson type anion (TeMo6O24)(6-). The polyoxometalates K-6n(TeMo6O24)(n)[(Ln(H2O)(7))(2)(TeMo6O24)](n).16nH(2)O (Ln=Eu, Gd) and K-3n[Ln(H2O)(5)(TeMo6O24)](n).6nH(2)O (Ln=Tb, Dy, Ho, Er) were characterized by X-ray structure analysis, elemental analysis and IR spectroscopy. We found that the solid-state structures of Ln/(TeMo6O24)(6-) compounds are strongly dependent on the lanthanide cations, and therefore represent a rare example for different arrangements of building units depending on the nature of the rare earth cations. While the Eu3+ and Gd3+ cations achieve ninefold coordination by seven water molecules and two terminal oxygen atoms of the (TeMo6O24)(6-) anions, the Tb3+, Dy3+, Ho3+ and Er3+ cations are coordinated by five water molecules, two terminal oxygen atoms and one molybdenum-bridging oxygen atom belonging to the (TeMo6O24)(6-) anion. The europium and gadolinium substituted compounds contain infinite one-dimensional [(Ln(H2O)(7))(2)(TeMo6O24)](n) chains; the terbium, dysprosium, holmium and erbium compounds contain infinite one-dimensional [Ln(H2O)(5)(TeMo6O24)](n)(3n)-chains.