Synthesis, Crystal Structure And Characterization Of Several Novel Tungstogermanates

The aim of this thesis is synthesis of new polyosometalate compounds on the basis of the rare reported tungstogermanates, which are bridged or decorated by various transition metal ions and organic N-containing ligands. Seven new polyoxometalate compounds have been synthesized on the basis of hydrothermal technique and water solution synthesis methods and structurally characterized by elemental analyses,IR,UV-vis and single crystal X-ray diffractions. The preliminary thermal stability and electrochemical properties were also investigated.1. Two new hexanuclear copper(â…¡) polyoxogermanotungstates decorated with transition metal complexes were prepared under hydrothermal condition:The compound 1 and 2 have the similar structure, the two half cells [B-α-GeW₉O₃₄Cu(en)(enMe)(H₂O)]^8-,which are connected by an inorganic-organic hybrid Cu₆(enMe)₂ or Cu₆(enMe)₂(H₂O)₂ cluster,further the formation of two-dimensional frameworks via the weaker Cu…O interactions. They are the first reported the Keggin-sandwichde Cu-6 tungstogermanates.2. Three new tetranuclear polyoxogermanotungstates decorated with transition metal complexes were prepared under hydrothermal condition:All the three compounds have the similar structure and contain four transition melals in the central belts. Compound 3 (4 or 5) consists of sandwich polyanions[Cu₄(B-α-GeW₉O₃₄)₂]^12- ([Zn₄(Hen)₂(GeW₉O₃₄₂]_10- or [Co₄(C₆H₁₄N₂)₂(GeW₉O₃₄)₂]^12-) linked by the bridges [Cu(en)₂]²⁺ ([Zn(en)₂]²⁺ or Co(C₆H₁₄N₂)₂²⁺) to form 2-D networks, which are further packed into a 3-D supramolecular porous framework via extensive hydrogen bonding interactions. Comound 5 represents the first example of POMs decorated by the complexes with 1, 2-diaminocyclohexane as organic ligands. 3. Two sandwich type tungstogermanates containing three or four Zr^4- cations in the central belt were prepared the conventionalsolution method:Polyanion [Zr₄O₂(OH)₂(CH₃COO)₂(α-GeW₁₀O₃₇)₂]^12-can also be considered as a dimer of acetate-functionalized di-Zr substituted [α-GeZr₂W₁₀O₃₈(OH)(CH₃COO)]^6- Keggin moiety, and each moiety contains two Zr atoms and both contained in one triad. One of the Zr atoms is seven-coordinate, and the other is eight-coordinate which is linked by an acetate group. The hypothetical [α-GeZr₂W₁₀O₃₈(OH)(CH₃COO)]^6- unit of 6 contains two Zr atoms in the same W₃O₁₃ triad. One of the Zr atoms is seven-coordinate, and the other is eight-coordinate which is bonded with an acetate group. The compound 7 consists of a [Zr₃O(OH)₂] triangular central cluster closely embedded between two A-α-[ GeW₉O₃₄]^10-subunits, leading to a "sandwich" type complex and it is the first one Zr-3 sandwich-like tungstogermanates.