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

摘要

A series of novel lanthanide polyoxomolybdates was synthesized by reaction of lanthanide cations with the Anderson type anion(TeMo_6O_24)~6-.The polyoxometalates K_6n(TeMo_6O_24)_n[(Ln(H2O)7)2(TeMo6O24)]_n(center dot)16nH_2O(Ln=Eu,Gd)and K_3n[Ln(H_2O)_5(TeMo_6O_24)]_n(center dot)H_2O(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/(TeMo_6O_24)~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 Eu~3+ and Gd~3+ cations achieve ninefold coordination by seven water molecules and two terminal oxygen atoms of the(TeMo_6O_24)~6-anions,the Tb~3+,Dy~3+,Ho~3+ and Er~3+ cations are coordinated by five water molecules,two terminal oxygen atoms and one molybdenum-bridging oxygen atom belonging to the(TeMo_6O_24)~6-anion.The europium and gadolinium substituted compounds contain infinite one-dimensional [(Ln(H_2O)_7)_2(TeMo_6O)_24)]_n chains;the terbium,dysprosium,holmium and erbium compounds contain infinite one-dimensional [Ln(H_2O)_5(TeMo_6O_24)]_n~3n-chains.