Syntheses, Characterizes And Properties Of The Transition-metal Derivatives Of γ-[GeW₁₀O₃₆]^8-

The aim of the thesis is the synthesis of novel transition-metal contained compounds based on transition-metal ions and divacant polyoxoanion precursorγ-[GeW₁₀O₃₆]^8-. The study on synthetic conditions and roles for these compounds and the exploration of relationships between structures of POMs and transition-metal ions are also carried out.Four transition-metal derivatives of POMs have been synthesized in aqueous solution and structurally characterized by single X-ray diffractions, elemental analyses, UV-vis, IR, TG. The magnetic behavior and electrochemistry behavior of these compounds have been studied.1. Two transition-metal ions branching sandwich-type POMs have been synthesized and characterized based on the improvement of the traditional synthesis method: K₄Mn₂(H₂O)12[Mn₄(H₂O)2Mn₂(H₂O)10(GeW₉O₃₄)₂]·17H₂O (1) K₄H4[Cu4(H₂O)2Cu2(H₂O)8(GeW₉O₃₄)₂]·18H₂O (2)Compounds 1 and 2 both have the similar building block. The building blocks were further connected into 1D chains by the branched transition-metal ions in 2.2. In the self-assembly process in water under different pH conditions, we obtain two trimeric tri-Ti-substituted polyoxometalates: K14{K?[(Ge(OH)O₃)(GeW₉Ti₃O₃₈H₂)₃]}·42H₂O (3) K10{K?[(SO4)(GeW₉Ti₃O₃8H3)3]·40H₂O (4)The two compounds are the first examples of Ti-substituted polyoxometalates as trimers. The novel Ge-O-Ti and S-O-Ti combination modes were observed in their structures. The isolation of the two trimers implies that the Ti-O-Ti anhydride is not the only combination mode of the oligomer in aqueous solution. It also shows a possibility to build large, multi-TiIV contained structures based on the TiIV-substituted POMs subunits and suitable linkers.