title: Solid-State and solution studies of [Ln(n)(SiW11O39)] polyoxoanions: an example of building block condensation dependent on the nature of the rare earth.
abstract: The reactivity of the [alpha-SiW(11)O(39)](8-) monovacant polyoxometalate with lanthanide has been investigated for four different trivalent rare-earth cations (Ln = Nd(III), Eu(III), Gd(III), Yb(III)). The crystal structures of KCs(4)[Yb(alpha-SiW(11)O(39))(H(2)O)(2)] x 24H(2)O (1), K(0.5)Nd(0.5)[Nd(2)(alpha-SiW(11)O(39))(H(2)O)(11)] x 17H(2)O (2a), and Na(0.5)Cs(4.5)[Eu(alpha-SiW(11)O(39))(H(2)O)(2)] x 23H(2)O (3a) are reported. The solid-state structure of compound 1 consists of linear wires built up of [alpha-SiW(11)O(39)](8-) anions connected by Yb(3+) cations, while the linkage of the building blocks by Eu(3+) centers in 3a leads to the formation of zigzag chains. In 2a, dimeric [Nd(2)(alpha-SiW(11)O(39))(2)(H(2)O)(8)](10-) entities are linked by four Nd(3+) cations. The resulting chains are connected by lanthanide ions, leading to a bidimensional arrangement. Thus, the dimensionality, the organization of the polyoxometalate building units, and the Ln/[alpha-SiW(11)O(39)](8-) ratio in the solid state can be tuned by choosing the appropriate lanthanide. The luminescent properties of compound 3a have been studied, showing that, in solution, the polymer decomposes to give the monomeric complex [Eu(alpha-SiW(11)O(39))(H(2)O)(4)](5-). The lability of the four exogenous ligands connected to the rare earth must allow the functionalization of this lanthanide polyanion.
authors.affiliation: Laboratoire de Physico-Chimie des Solides Moléculaires, Institut Lavoisier, UMR 8637, Université de Versailles Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles Cedex, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Mialane
authors.forename: Laurent
authors.initials: L
authors.lastname: Lisnard
authors.forename: Alain
authors.initials: A
authors.lastname: Mallard
authors.forename: Jérôme
authors.initials: J
authors.lastname: Marrot
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Antic-Fidancev
authors.forename: Patrick
authors.initials: P
authors.lastname: Aschehoug
authors.forename: Daniel
authors.initials: D
authors.lastname: Vivien
authors.forename: Francis
authors.initials: F
authors.lastname: Sécheresse