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1D Polyoxometalate-Based Composite Compounds Derived from the Wells−Dawson Subunit: Synthesis and Crystal Structure of [{Ce(DMF) 4 (H 2 O) 3 }{Ce(DMF) 4 (H 2 O) 4 }(P 2 W 18 O 62 )]·H 2 O and [{La(DMF) 6 (H 2 O)}{La(DMF) 4.5 (H 2 O) 2.5 }(P 2 W 18 O 62 )]

2004; American Chemical Society; Volume: 4; Issue: 2 Linguagem: Inglês

10.1021/cg034131y

1528-7505

Jingyang Niu, Dongjie Guo, Jingping Wang, Junwei Zhao,

Vanadium and Halogenation Chemistry

Two composite compounds, [{Ce(DMF)4(H2O)3}{Ce(DMF)4(H2O)4}(P2W18O62)]·H2O (1) (DMF = N,N-dimethylformamide) and [{La(DMF)6(H2O)}{La(DMF)4.5(H2O)2.5}·(P2W18O62)] (2), have been constructed at room temperature and characterized by single crystal X-ray structural analyses, ESR spectroscopy, and thermogravimetric (TG) and differential thermal analysis (DTA) measurements. Single crystal X-ray structural analyses reveal that the adjacent polyanions are polymerized to form a 1D infinitely linear chain by the bridging RE coordination cations and exhibit an -ACACAC- type of structure, and that two types of terminal oxygen atoms of the Wells−Dawson polyanion located in the "cap" and "belt" sites are involved in coordination with the RE3+ ions, respectively. ESR spectra indicate that after irradiation with sunlight, compound 2 forms a mixed-valence heteropoly compound with unshared electrons. From TG-DTA analyses, we surmise that the frameworks of polyanions of this kind of compound decompose at ca. 620 °C.