| Polyoxometalates (POMs) represent a fascinating class of inorganic chemistry with a structural variety and interesting properties, which are of use in fields as diverse as catalysis, sorption, molecular electronics, medicine, etc. As the applications of hydrothermal technique on the syntheses, various organic-inorganic hybrid materials of particular properties emerges constantly and much attention has been caused on the performances studies of various materials. In this field, an important advance is to decorate well-known polyoxoanions with various organic and/or transition metal complex moieties and then to link them up into one-, two-, even three-dimensional extended solid materials in appropriate ways. The introduction of metal complex can not only enrich the frameworks of polyoxometalates but also ameliorate their electronic and mangnetic properties. Based on this mechanism, we synthesized some non-classical metal-oxygen clusters, the cluster-polymers based on tungsten-vanadium and molybdenum- vanadium oxygen clusters. On the bases of X-ray structural analyses, some central compounds have been characterized by IR, XPS spectra. The thermal analyses and magnetic properties of some compounds have been studied, which would take an important role in the explorations of structures and functions for the compounds. I Keggin-structure tungsten-vanadium oxygen clustersApplying in hydrothermal synthesis reactions, we synthesized three Keggin-structure tungsten-vanadium oxygen clusters. [Ni(2,2'-bipy)3]1.5{PW10.79 V1.21O40(VO)0.5[Ni(2,2'-bipy)2L]}·0.5H2O 1, [Cu4(2,2'-bipy)4(H2O)2(PO4)2]H6.5[P W8.36V3.64O40]·2H2O 2, [Cu(2,2'-bipy)3]2H14{PW2V10O40(VO)2[Cu(2,2'-bipy)2 H2O]2}[PW2V10O40(VO)2]·10H2O 3. Compound 1 is composed of the {PW10.79V1.21 O40(VO)0.5[Ni(2,2'-bipy)2L]}3-, which is further linked into a novel dimer through hydrogen bonging. Compound 2 is composed of an unusual Keggin [PW8.36V3.64 O40]4- cluster and a novel transition metal complex [Cu4(2,2'-bipy)4(H2O)2 (PO4)2], which has 1D chain structure, is based on the Keggin structure tungsten-vanadium cluster [PW8.36V3.64O40]4- linked by [Cu4(2,2'-bipy)4(H2O)2(PO4)2]. The sturucture of compound 3 features a novel 2D supramolecular layer built from the bicapped Keggin [PW2V10O40(VO)2]11- anions are decorated with [Cu(2,2'-bipy)2H2O]2+ unit and the discrete bicapped Keggin [PW2V10O40(VO)2]11- anions having a high V/W ratio. The X-ray single crystal analysis, elemental analysis, IR, XPS and TG etc., have been performed on these compounds. Variable-temperature magnetic susceptibility measurements reveals the feature of ferromagnetic exchange of compound 1 and the feature of antiferromagnetic exchange of compounds 2 and 3.II Keggin-structure molybdenum-vanadium oxygen clustersApplying in hydrothermal synthesis reactions, we synthesized four Keggin- structure molybdenum-vanadium oxygen clusters. [Cu(2,2′-bipy)][Cu(2,2′-bipy)2]2 [PMo8V6O42]·1.5H2O 4, [Cu(2,2′-bipy)][Cu(2,2′-bipy)2]2[PMo8V6O42]·2H2O 5, [Co(2,2'-bipy)3]2{PMo12O40(VO)2[Co(2,2'-bipy)2(H2O)]2}[PMo12O40(VO)2]·{(OH)10} 6, [PMo12V6O46]{(OH)9}·7H2O 7. Compounds 4 and 5 feature a bi-capped keggin molybdenum-vanadium polyoxoanion, which is further interconnected with [Cu(2,2′-bipy)]2+ and [Cu(2,2′-bipy)2]2+ groups via the terminal oxygen atoms of polyoxoanions to form a tri-supported unit. Compound 6 features a bi-capped keggin molybdenum-vanadium polyoxoanion, which is further interconnected with [Co(2,2'-bipy)2(H2O)]2+ groups via the terminal oxygen atoms of polyoxoanions to form a bi-supported unit. Compound 7 is decorated with six (VO)2+ based on the [PMo12O40]3-. The X-ray single crystal analysis, elemental analysis, IR, XPS and TG etc., have been performed on these compounds. Variable-temperature magnetic susceptibility measurements of compounds 4 and 5 reveal the feature of ferromagnetic exchange.III Keggin-structure tungsten oxygen clustersApplying in hydrothermal synthesis reactions, we synthesized four Keggin- structure tungsten oxygen clusters. K[PW12O40[Ni(1,10-phen)2(OH)]2]·2H2O 8, (4,4′-bipy)4H3[PW12O40]·6H2O 9, (4,4′-bipy)8H9[P1W12O40]2[P1W12O40]·10H2O 10, [SiW12O40[Co(1,10-phen)2(H2O)]2]·3H2O 11. Compound 8, which has 1D chain structure, is based on the bi-supported Keggin structure tungste cluster [PW12O40 [Ni(1,10-phen)2(OH)]2]- linked by the alkali metal ion K+ bridges. Compounds 9 and 10 are compounds, which are composed of the classical keggin polyoxoanion [PW12O40]3- and the 4,4′-bipy units. Compound 11 features a keggin molybdenum polyoxoanion [SiW12O40]3-, which is further interconnected with [Co(1,10-phen)2 (H2O)]2+ groups via the terminal oxygen atoms of polyoxoanions to form a bi-supported unit. The X-ray single crystal analysis, elemental analysis, IR, XPS and TG etc., have been performed on these compounds. The magnetic behavior of compound 8 was measured, and these data between 50 K and 250 K is coincident with the Curie-Weiss law, the Weiss Constant is big than zero, which indicates the presence of ferromagnetic interaction between the metal ions of them. Unfortunately, it is too difficult to fit the experimental mangentic data of these hetero-polymetallic spin systems using a suitable theoretical model.IV molybdenum oxygen clustersApplying in hydrothermal synthesis reactions, we synthesized two molybdenum oxygen clusters. [Ni(1,10-phen)3]2[PMo12O40]·2H2O 12, (4,4′-bipy) [As2Mo18O62As2]·3H2O 13. Compound 12 is composed of the classical keggin polyoxoanion [PMo12O40]3- and the transition metal complex units [Ni(1,10-phen)3]2+. The polyoxoanions of Compound 13 is decorated with two (AsO) unit based on the classical Dawson polyoxoanion [As2Mo18O62]3-. The X-ray single crystal analysis, elemental analysis, IR, XPS and TG etc., have been performed on these compounds.V vanadium oxygen clustersApplying in hydrothermal synthesis reactions, we synthesized two vanadium oxygen clusters. [Cu(2,2'-bipy)2]2[(V3O8.5)2] 14, [Zn(2,2'-bipy)]2[(V4O10.5)2] 15. Compound 14 exhibits an interesting 2D framework based on [(V3O8.5)2]4-. Compound 15 features a 2D network built from [(V4O10.5)2]4-. The X-ray single crystal analysis, elemental analysis, IR, XPS and TG etc., have been performed on both two compounds. The magnetic behavior of compound 14 was measured, and the data indicates the existence of ferromagnetic coupling of eleven V(IV) and three Ni(II) ions.
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