The Design And Syntheses Of Inorganic-organic Complexes Based On Lacunary Polyoxotungstates(Molybdates)

In modern society,researchers in various disciplines have been making great progresses in addressing scientific problems with the discovery of novel materials.In the field of coordination chemistry,polyoxometalates?POMs?,known for their diverse structures and capability to coordinate with organic ligands to form new hybrid molecules,have attracted considerable attention.The main purpose of this project is to synthesize new hybrid molecular materials from polyoxometalates and organic ligands,either with or without transition metal ions.This paper describes experimental details for the preparation of a number of precursors,including inorganic POM ligands,organic linkers,and secondary metal sources.For inorganic POMs,we have prepared five different types of water-soluble polyoxometalates and also a counterion exchanged derivative that is soluble in organic solvents.We also designed and synthesized a new type of diphosphonate organic linker with the formula H₂O₃PC₄H₈PO₃H₂,abbreviated as C₄.As for the secondary metal source,we use a multi-Mn cluster,[Mn₁₂O₁₂?O₂CCH₃?₁₆?H₂O?₄]�2CH₃COOH�4H₂O(abbreviated as Mn₁₂)as the main source of substituting metal ions.A "POM-organic-ligand"-type hybrid molecule,compound 1,is constructed from the reaction of polyoxomolybdate with carboxyl-or phosphonate-based organic ligands.The structure of this compound is first confirmed by single-crystal X-ray diffraction,which is then supported by various spectroscopic techniques.The oxidation states of the molybdenum sites are confirmed by the BVS?Bond Valence Sum?calculations.The molecular formula is as follows,Na₂₅[(Mo₆^VO₁₅)₂(Mo₃^VIO_13.5)₂?O₃PC₆H₅?₈]�8H₂O.The second hybrid molecule is of the "POM-metal-organic-ligand"-type,prepared from lacunary POMs,transition metal ions and a diphosphonate-based organic ligand,and referred to compound 2.This compound,also analyzed with single-crystal X-ray diffraction,is of the formula Na₃[?CH₃?₂NH₂]₂₀[{Mn^?Mn₃^?O₄Ac₂(Si W₉O₃₄H)}₂{Mn^?Mn₃^?O₄Ac₃(Si W₉O₃₄H)}{Mn₂^?O(Si W₁₀O₃₇H)}?C₄H₈P₂O₆?]�20H₂O.In summary,in this paper we have used two different strategies for the syntheses of hybrid molecules,taking into account of the spatial characteristics of the organic and inorganic precusors so that specific polyhedral structures could be generated.The author has succeeded in synthesizing hybrid molecules using both methods,setting the stage for future targeted design and synthesis of new molecular materials.