The Study Of Molybdenum Cluster Polyoxometalates Compounds And Tungsten Cluster Polyoxometalates Compounds

The aim of this thesis is the synthesis of new a series of molybdenum clusters compounds and tungsten clusters compounds via water solution synthesis methods. The study on synthetic conditions and rules for these new compounds are also carried out. The new polyoxometalate compounds have been synthesized on the basis of hydrothermal technique and structurally characterized by elemental analyses, IR, EPR, TG, CV and single crystal X-ray diffractions.1. Three new polyoxometalates clusters have been water solution synthesized and structurally characterized: Na5(NH4)16[Mo57Mn6(NO)6O174(OH)3(H2O)24]·44H2O (1) (NH4)21[Mo57Cu6(NO)6O168(OH)3(H2O)24]·53H2O (2) Na13[HMoV12MoVI6O54(HCOO)2]·32H2O·2HCOOH·HCl (3)These clusters have high degree of polymerization, with mixed valence state, as well as striking the topological characteristics. Preparation of such compounds has one most important strategie, which adopted by the self-assembly process generating relatively large the intermediates in the solution, and prevent unrestricted plastic or even precipitation, therefore ensure a higher intermediate solubility and slowly produce crystal. In polymolybdate, the initial raw materials's reducing vulnerability and the related intermediate products in the reaction are prerequisite for the growth of crystal. Reduction can increase clusters'pro-nuclear in regions outside of them.2. Five new polyoxometalate compounds on the basis of [BiW9], [CoW9] polyoxoanion cluster have been synthesized and structurally characterized: K2.5Na5(NH4)23Ag7.5W10O31(BiW9O33)4·32H2O (4) KNa5(NH4)14Ag3W3Bi2(H2O)2O10(BiW9O33)3·34H2O (5) K2Na6(NH4)6[(VO)2(BiW9O33)2]·41H2O (6) Na12H2[Co2Bi2(CoW9O34)2]·50H2O (7)These tungsten clusters have high degree of polymerization properties. The main influencing factors of preparation of these compounds are PH reaction, the reaction temperature and reaction time as well as the introduction of bridged fragments. The formation of tungstenn clusters in the acidification process has strong W-W metal interaction. In order to make the absence Tungsten fragment further effective connectivity, we have been introduced appropriate "linking agent" such as transition metal ions and auxiliary vacancy fragment to formed high tungsten cluster compounds in the reaction.3. One new polyoxometalates compounds on the basis of [W12] polyoxoanion cluster and Main group mental have been synthesized and structurally characterized: (NH4)7[Bi(H2W12O42)]·20H2O (8)The compound 8 represents the new compound of polyoxometalate basic structural unit which has been a very forefront of the field of the subject. We use polyoxometalates [H2W12O42] 10- as the basic building units which are covalently linked by the main group mental used as connectors into a 1D structure. To our knowledge, it represents the first a main group metal Bi joining compounds, the structure of this structure represents not only a new type of one-dimensional chain structure, but also show that using polyoxometalate flexible ligand to build a new 3-D structural support.