Synthesis, Structure And Characterization Of Novel Polyoxometalates Decorated By Lanthanide-Organonitrogen Compounds

The aim of this thesis is the synthesis of new polyoxometalate compounds on the basis of Keggin and Wells-Dawson-type polyoxoanion clusters, which are decorated or bridged by various Lanthanide complexes. The study on synthetic conditions and rules for these new compounds are also carried out.Nine new polyoxometalate compounds have been synthesized on the basis of conventional solution method and structurally characterized by elemental analyses, IR, TG, single crystal X-ray diffractions.electrochemical and caloric stability are studied.1. Five new compounds on the basis of [H2W12O40]6- polyoxoanion cluster that are decorated or bridged by various Lanthanide complex , have been conventional solution method and structurally characterized: [H₂bpy][Ce(DMF)₄(Hbpy)(H₂O)₃][H₂W₁₂O₄₀]～10H₂O (1) [H₂bpy][La(DMF)₄(Hbpy)(H₂O)₃][H₂W₁₂O₄₀]·4H₂O (2) [Hbpy]₂[Ce(DMF)₅(Hbpy)(H₂O)₂][H₂W₁₂O₄₀]·0.5H₂O (3) [H₃O]₂[La(Hbpy)(H₂O)₇][H₂W₁₂O₄₀] (4) [(CH₃)₂NH₂]₂[H₂bpy][Hbpy]₂[H₂W₁₂O₄₀]·3H₂O (5) (DMF = N,N-dimethylformamide,bpy = 4,4'-bipyridine)double chain - like supramolecular structure. The one - dimensional double chains are further extended to a two - dimensional layer structure via hydrogen bonds. Compound 5 shows a 3D supramolecular structure. Furthermore, the electrochemical properties of the compound 2, 3, 5 has been studied via the method of bulk-modified carbon paste electrodes. we find (CH₃)₂NH molecular in the title compound 5, We think this originates from the hydrolysis of DMF under the catalysis of [H₂W₁₂O₄₀]^6-.2. Three new polyoxometalate compounds on the basis of molybdenum phosphates polyoxoanion cluster decorated by Lanthanide - organonitrogen complex have been conventional solution method and structurally characterized: [La(DMF)₇(H₂O)][PMo₁₂O₄₀]·DMF·(CH₃)₂NH (6) (H₃O)₃[Nd(DMF)₄(H₂O)₅][P₂Mo₁₈O₆₂]·DMF (7) [Nd(DMF)₅(H₂O)₃][Nd(DMF)₅(H₂O)₂][P₂Mo₁₈O₆₂] (8)Compound 6 exhibits Lanthanide complexes supporting Keggin-type molybdenum phosphate cluster structure. This kind of weak interaction results in a one - dimensional double chain - like supramolecular structure via hydrogen bonds. The one - dimensional double chains are further extended to a two - dimensional layer structure via hydrogen bonds. In compound 7, 8 are Wells-dawson-type molybdenum phosphate cluster structure, shows a one - dimensional supramolecular structure via weak interaction. we find (CH₃)₂NH molecular in the title compound 6, We think this originates from the hydrolysis of DMF under the catalysis of 12 - molybophosphate.3. we have focus on studying the reaction of the monovacant Keggin-type silicotungstates with lanthanide cations in the existence of the alkali metal ion CsI. we synthesized and characterization of a new dimeric complex : Cs₁₀Na₃[Ce(SiW₁₁O₃₉)₂]·13H₂O (9)In compound 9, Two [SiW₁₁O₃₉]^8- polyanions connected by a hexa-metal cluster Ce^IIICs₅ to a dimer. Adjacent [Ce^IIICs₅ (SiW₁₁O₃₉)₂] units connected by sevral Cs^I iron to a 1D chainlike,2D layer structure. Furthermore, the electrochemical properties and caloric stability of the compound 9 has been studied.