Effect of ionic radii of lanthanide ions on reaction with A-PW9[image omitted]. Synthesis and characterization of [(A-PW9O34)2(H2OM)3CO3]11-(M=Eu3+, Gd3+) and [(W5O18)2M]9-(M=Pr3+, Nd3+)

The reaction of A-PW9[image omitted] with carbonate solution of lanthanide ions produces different products under the same conditions. The sandwich-type complexes of [(A-PW9O34)2(H2OM)3CO3]11- are the main products of the reaction of A-PW9[image omitted] with Eu3+ and Gd3+ while, with Pr3+ and Nd3+ products are decatungstometalate complexes [(W5O18)2M]9-. The products have been isolated and characterized by elemental analysis, infrared, 31P NMR spectroscopy, thermogravimetric analysis (TGA), and single crystal structure analysis. The structures of the first complexes consist of two trivacant polyoxometalates A-PW9[image omitted] which are linked by a (MOH2)3CO3 belt. The 3 vibrational band of [image omitted] at 1471-1485 cm-1 and a break in the TGA curves at 425 degrees C confirm the presence of coordinated [image omitted] in the structures. The single crystal structure analysis was carried out on K6Na2(H3O)[(W5O18)2Pr] center dot 18H2O (H38K6Na2O55PrW10). The anion consists of two [W5O18]6- linked via Pr3+. The Pr3+ is eight coordinate with overall anion symmetry close to D4d.