Synthesis, And Structures And Spectroscopic Characterization Of Compounds Based On Covalently Bonded Organic-Polyoxomolybdates

Polyoxometalates (POMs) are a unique class of metal-oxygen clusters, coupled with interesting electrical and optical properties such as electrochromism, photochromism, conductivity, and redox activitities. The molecular nature of POMs and conjugated organic molecules offers the opportunity to generate covalently bonded molecular hybrids where the interplay between cluster d electrons and organic delocalized Ï€-electrons can be explored at the molecular level. Such materials have drawn tremendous attention in the last decade and have found numerous exciting applications in, light emitting diodes, and field-effect transistors and solid-state lasers. Among the many organic derivatives of POMs, organoimido derivatives have attracted particular interest.The time of structure scissor and self-assembly in synthesis of polyoxometalatesis coming, and now a quantity of polyoxometalates with novel structure were synthesized with the organic templated directing. Polyoxometalates have received a lot of interest in research because of their potential applications in the areas such as catalysis, medicine and functional materials. Based on the systematic investigation on the literature in polyoxometalates research, we carried out the study on the synthesis, structures and spectroscopic characterization of compounds of based on covalently bonded organic-polyoxomolybdates with several arylimido derivatives and alanines, and intended to find the relationship between properties and structures, discussed the reaction activity center and inferred the reaction mechanism. Upon that, this dissertation falls to doing works running after this hot point. We synthesized three new organoimido derivatives of hexamolybdates[n-Bu₄N_]2[Mo₆O₁₇(=NC₆H₃(MeO)₂-o, p)₂] (â… ), [n-Bu₄N]₂[Mo₆O₁₇[(=NC₆H)3-2-C₂H₅-6-CH₃)₂] (â…¡), [n-Bu₄N]₂[Mo₆O₁₇[(=NC₆H₃-2-CH(CH₃)₂-6-CH₃)₂]-H₂O (â…¢) and a new octamolybdate coordinating two alanine ligands,K₄[Mo₈O₂₆(CH₃CH(NH₃)CO₂)₂]·4H₂O (IV), and determined their structures. At the same time, we unexpectedly synthesized an unusual crystal in which [MO₆O₁₉]^2-coexist with a-JMogC^]4" anions, [n-Bu4N]g[Mo6Oi9]2[a-(Mo8O26)] (V), while trying to synthesize a desired hybrid molecular dumbbells with two POM clusters and aromatic amine in the anhydrous acetonitrile solution. In fact, the pH-dependence and hydrolytic complexity of polyoxomolybdates make the direct determination of such coexistence very difficult. To the best of our knowledge, this is the first compound in which [MO6O19J2" coexist with a-[MogO26]4" anions in the same crystal architecture. In view of the extensive contemporary interest in POMs, the work is both timely and significant. The result also provides a useful information to develop crystal engineering based on different POM building blocks.All the new complexes were characterized by Elemental analysis, IR, UV-Vis and X-ray single-crystal analysis. The compounds (I), (II) and (III) were also characterized by *H NMR and the compound (V) was also characterized by thermogravimetric analysis.