Studies On Syntheses And Structures Of Organoimido Derivatives Of Hexamolybdates And Their Metal Complexes

Polyoxometalates (POMs) are a class of inorganic cluster compounds consisting ofearly transition metal cations and oxygen anions. Because of their diverse structures andnanoscale size, POMs have fascinating photonic, electronic and magnetic properties,special catalytic and medical activities as well. The modification of POMs with organicligands, through which the properties of POMs can be tuned, has obtained broad anddeep focus in recent years. As one important method of modification, the imidoylizationof POMs connects the organic ligand and inorganic cluster covalently through nitrogenatom. The organoimido derivatives not only combine the properties of organic andinorganic parts but also bring synergistic effects, resultiong in new properties. Theorganoimido derivatives of POMs with remote groups can undergo further reaction toget organic-inorganic hybrid materials with novel structures and properties. Based onprevious researches, we synthesized a series of organoimido derivatives ofhexamolybdates containing carboxyl, hydroxyl and ester group by DCC(N,N’-dicyclohexylcarbodiimide) protocol, then we obtained the metal complexesthrough the coordination of copper and zinc ions, the structures of which werecharacterized.There are three parts in this work as follows: Firstly, four organoimido derivativesof hexamolybdates with carboxyl group were synthesized with octamolybdate andhydrochloride as reactants. The structures of products were characterized and analyzed,which shows that different hydrogen bonding interactions make the supramolecularassembly behaviors of the products different althrough the organic ligands are similar.Secondly, three organoimido derivatives of hexamolybdates with ester, hydroxyl andcarboxyl group were synthesized with hexamolybdate and amine or sodium salt asreactants. The studies show that some organoimido derivatives of hexamolybdates withelectron withdrawing group can be obtained with hexamolybdate as reactant and that thecarboxyl group is formed from the carboxylate anion during the imidoylization reaction.Thirdly, five metal complexes were synthesized through the coordination of copper, zincions and organoimido derivatives of hexamolybdates containing carboxyl group. Theresults show that the copper complex present a windmill-like structure with four large hexamolybdate clusters extending outside and a dinuclear copper unit, that thedifference of the organic ligands affects crystal formation of the metal complex andarrangement orderliness of the groups in the crystal structure. This work enriches thecategory of organoimido derivatives of hexamolybdates to some extent, provides someinformation on the research of reaction mechanism, and creates conditions for thetheoretical and application research on the coordination assemblies of polyoxometalatesderivatives.