RESUMO
A systematic study of the condensation reactions of arylarsonic-functionalized [α-P2W12O48]14- units in acidic aqueous media identified that the specific presence of an amino group in the ortho position of the phenyl rings induces a dimerization process that allowed isolation of discrete dimeric polyanions [(o-H2N-C6H4-AsO3)4P4W24O85]14- (1) with an unprecedented polyoxometalate skeleton characterized by two seminal {P2W12} groups joined via a single W-O-W bridge. At the same time, addition of divalent transition metal ions (MnII, CoII, and NiII) in the reaction mixture directed a condensation process on a completely different pathway resulting in one-dimensional (1D) coordination polymers based on V-shaped [{M(H2O)4}P4W24O92(C6H6AsNO)2]14- polyanions (M = MnII (2), CoII (3), and NiII (4)). All polyanions were isolated as hydrated mixed potassium/dimethylammonium salts and thoroughly characterized in the solid state. 31P NMR studies showed that the discrete cluster 1 is comparatively stable in 1 M LiCl aqueous solution and thus represents a potential precursor for subsequent reactions.
RESUMO
A family of solution-stable polyanions [Naâ{LnIII (H2 O)}{WVI O(H2 O)}PV 4 WVI 26 O98 ]12- (Ln=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) represent the first examples of polyoxometalates comprising a single lanthanide(III) or yttrium(III) ion in a rare trigonal prismatic O6 environment. Their synthesis exploits the reactivity of the organophosphonate-functionalized precursor [P4 W24 O92 (C6 H5 PV O)2 ]16- with heterometal ions and yields hydrated potassium or mixed lithium/potassium salts of composition Kx Lny H12-x-y [Naâ{Ln(H2 O)}{WO(H2 O)}P4 W26 O98 ]â nH2 Oâ mLiCl (x=8.5-11; y=0-2; n=24-34; m=0-1.5). The Dy, Ho, Er and Yb derivatives are characterized by slow magnetization relaxation.
RESUMO
The propensity of the new, phenylphosphonate-stabilized polyoxotungstate [(C6 H5 PV O)2 P4 W24 O92 ]16- to act as a precursor for new 3d metal-functionalized polyanions has been investigated. Reactions with MnII and CuII induce the formation of the previously unknown polyoxotungstate archetype {P4 W27 }, isolated as salts of the polyanions [Naâ{MnII (H2 O)}{WO(H2 O)}P4 W26 O98 ]13- (1) and [Kâ{CuII (H2 O)}{W(OH)(H2 O)}P4 W27 O99 ]14- (2), which were characterized in the solid state (single-crystal X-ray diffraction, elemental and TG analyses, IR spectroscopy, SQUID magnetometry) and in aqueous solution (UV/Vis spectroscopy, cyclic voltammetry).
RESUMO
Controlled isomerization of individual {α-P2W12O48} polyoxotungstate building blocks under the constricted conditions of the macrocyclic [P8W48O184]40- archetype ({P8W48}) is linked to site-specific CuII coordination. The derivatives [αγαγ-P8W48O184{Cu(H2O)}2]36- (1), [γγγγ-P8W48O184{Cu(H2O)0.5}4]32- (2), and [αγγγ-P8W48O184{Cu(H2O)}3]34- (3) feature the {αγαγ-P8W48} and the hitherto unknown {γγγγ-P8W48} and {αγγγ-P8W48} isomers based on {α-P2W12} and/or CuII-stabilized {γ-P2W12} units and form from the reactions of the classical {P8W48} (={αααα-P8W48}) and CuCl2 in sodium acetate medium (pH 5.2). All products were thoroughly characterized in both the solid state and aqueous solutions, including electrocatalysis assessments.