Hydrothermal syntheses and structural characterizations of polyoxometalate (Mo/W) compounds consisting of M-L cations, (M = Mn, Co, Ni, Cu, Zn; L = 3-(2-Pyridyl)pyrazole)

Document Type

Article

Publication Date

10-7-2009

Abstract

A series of molybdenum/tungsten polyoxometalate compounds, namely, [(M II(HL)2)Mo3O10] (M = Mn (1), Co (2), Ni (3)), [CuII2(L)2(HL)2] 2(Mo8O26) (4), [Zn(HL)2(MoO 4)]2·HL·4H2O (5), [Cu II4(L)6WO4)]·3H2O (6) (HL = 3-(2-pyridyl)pyrazole), were designed and synthesized under hydrothermal conditions. X-ray diffraction analyses reveal that compounds 1-3 have an isostructural, wavelike chain structure consisting of the asymmetric building blocks of [Mo3O10], in which the ratio of octahedron {MoO6} and square pyramid {MoO5} is 1:2. The hexacoordinated transitional metal cation, just like one "anchor" to fix the above wavelike chain, is linked by two terminal oxygen atoms belonging to two edged asymmetric molybdate [Mo3O10]2- units, and further chelated by two 3-(2-pyridyl)pyrazole ligands. Although a similar synthetic method in preparation of 1-5 was employed, compounds 4 and 5 show a completely different structure compared to compounds 1-3. Compound 4 is composed of two separate parts of the [CuII2(L) 2(HL)2]2+ dimer and the ε-[Mo 8O26]4- unit. Compound 5 consists of a bimetallic tetranuclear cluster that is constructed from corner-sharing {MoO4} tetrahedra and (ZnN4O2) distorted octahedron forming a cyclic (Zn2Mo2O4) core. For compound 6, a one-dimensional structure is composed OfWO42- linked by the centrosymmetric tetranuclear copper grids, in which two approximately planar [CuII(L)]2 units with an inversion center stack parallel and face-to-face linked by two additional deprotonated ligands of L-1 perpendicularly. © 2009 American Chemical Society.

Publication Source (Journal or Book title)

Crystal Growth and Design

First Page

4424

Last Page

4428

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