Large heteropolymetalate complexes formed from lanthanide (Y, Ce, Pr, Nd, Sm, Eu, Gd), nickel cations and cryptate [As4W40O140]282: synthesis and structure characterization

A new family of heteropolytungstate complexes (NH4)21[Ln(H2O)5{Ni(H2O)}2As4W40O140]·xH2O(Ln ¼ Y, Ce, Pr, Nd, Sm, Eu, Gd) were prepared by the reaction of Na27[NaAs4W40O140]·60H2O with NiCl2·6H2O and Ln(NO3)3·xH2O at pH < 4.5. The crystal structures of (NH4)21[Gd(H2O)5{Ni(H2O)}2As4W40O140]·51H2O was determined by X-ray diffraction analysis and element analysis. The compound crystallizes in the monoclinic space group P21=n with a ¼ 19:754ð3Þ; b ¼ 24:298ð4Þ; c ¼ 39:350ð6Þ A; b ¼ 100:612ð3Þ8; V ¼ 18564ð5Þ A3; Z ¼ 2; R1ðwR2Þ ¼ 0:0544ð0:0691Þ: The central site S1 and two opposite sites S2 of the big cyclic ligand [As4W40O140]282 are occupied by one Ln3þand two Ni2þ, respectively, each site supply four Od coordinating to metal ion, another one water molecule and other five water molecules coordinate, respectively, to Ni2þand Ln3þ. Polyanion [Ln(H2O)5{Ni(H2O)}2As4W40O140]212 has C2v symmetry. IR and UV–vis spectra of [NaAs4W40O140]272 of the title compounds are discussed. q 2004 Elsevier B.V. All rights reserved.