Hydrothermal Synthesis, Structure And Characteration Of The Substituted Lacunary Tungsten-Oxo Clusters

The research work of this thesis is directed by the synthetic consideration that the lacunary sites of lacunary polyoxotungstates (POTs) can act as structure-directing agents to induce the formation of the second transition-metal (TM) clusters which was initiated by our group. Therefore many researchers were being interested in it. As a branch of POMs, transition-metal-substituted polyoxometalates (TMSPs) also show the unique status in this field, and the research of oxo tungsten cluster was the most widely. The study of initial saturated structures has been replaced by the novel and changeable high nuclear clusters and multi-dimensional fameworks. We introduced lacunary precursors K8Na2[A-a-GeW9O34]-25H2O and Na9[A-a-PW9O34]·7H2O, different TMs or3d,4f elements into reaction system to obtain novel TMSPs under the medium and low temperature hydrothermal conditions. Fortunately, ten novel oxo tungsten clusters have been successfully synthesized and characterized by single-crystal X-ray diffraction, Infrared spectra, elements analysis and powder X-ray diffraction, also their thermal stabilities have been investigated.The formulas of these compounds are as follows:[Ni(H2O)(en)2][WO4]{[Ni6(OH)3(H2O)2(en)3(Im)2](B-a-PW9O34)}-2H2O (3-1)[Ni6(OH)3(Im)3(1,2-dap)3](B-a-PW9O34)][Ni6(OH)3(Im)4(1,2-dap)3-(3-2)(B-a-PW9O34)]-8H2O K[Na(H2O)]2H3[Co4(H2O)2(JB-a-GeW9O34)2]·3(H2en)·7H2O (3-3)[Zn(2,2’-bpy)(H2O)4]2[Na(H2O)]2{{[Zn(2,2’-bpy)(H2O)3]2[Zn(2,2’-bpy)]2Zn4(H2O)2-(GeW9O34)2}[KNa(H2O)]2[Na(H2O)4.5]2{[Zn(2,2’-bpy)]2Zn4(H2O)2-(4-1)(B-a-GeW9O34)2}·22H2O [Na(H2O)2.5]2[Zn(2,2’-bpy)2(H2O)]2[Zn6(2,2’-bpy)2(B-a-PW9O34)2]·15H2O (4-2)(ZnH2O)2Zn2[Zn(Im)3H2O]2(5-a-HGeW9O34)2-2[Zn(Im)3H2O]·2(HIm)-8H2O (4-3) H2(enH2)2[Zn(en)2(enH)]{[Zn(enH2)(en)0.5][Zn2(enH)(B-a-GeW9O34)]}[Zn2(enH)-(4-4)(B-a-GeW9O34)]·8H2O H4(enH2)3{K2(H2O)8[Zn(en)2]2[Zn4(H2O)2(B-a-GeW9O34)2]}{Zn(en)2[Zn(en)2]2-(4-5)[Zn4(enH)2(JB-a-GeW9O34)2]}·28H2O Na2KLa3(H2O)24[Zn4(H2O)2(B-α-GeW9O34)2]·12H2O (4-6)[K2(H2O)3]2Cd2(H2O)6Cd (H2O)8[(CdH2O)Cd(B-α-HGeW9O34)]2·12H2O (4-7)en=1,2-ethylenediamine, Im=imidazole,1,2-dap=1,2-propyleneamide,2,2-bpy=2,2’-dipyridylCompound3-1is a novel octanuclear heterometallic {Ni6WNi}-substitutedKeggin-type phosphotungstate with mixed organic ligands of en and Im, the most strikingstructural feature of the heterometallic {Ni6WNi} cluster is incorporating a WO4tetrahedron.Compound3-2is very similar to compound3-1with mixed organic ligands of en andIm. But there exists two kinds of cluster only differs by a imidazole ligand forming theone-dimensional chain alternately. Compound3-3contains tetra-Co sandwiched dimericcluster and further linked by Na+and K+to construct a2-D layer.Compounds4-1to4-6are all Zn-substituted sandwiched oxo tungsten clusters,4-1and4-2are constructed by2,2’-bpy. Compound4-1contains four kinds of Zn+, compound4-2contains hexa-Zn cluster with a rare belt motif.4-3to4-5are isolated tetra-Znsubstituted sandwich-type units with different organic amine. Compounds4-6is a novelZn-La substituted phosphotungstate bridged by La+. Compound4-7is a tetra-Cd subsitutedsandwich-type phosphotungstate connects with other six units.The successful syntheses of the above oxo tungsten clusters not only enrich thestructural chemistry of oxo clusters, but also provide the new route to the development ofhigh-nuclear TMSPs and POTs built by different oxo tungsten cluster fragments and3d-4fheterometallic clusters.