Font Size: a A A

Coordination Assembly, Crystal Stucture And Magnetism Of The Trilacunary Keggin-Type Polytungstates And Transition Metals

Posted on:2008-04-24Degree:DoctorType:Dissertation
Country:ChinaCandidate:H LiuFull Text:PDF
GTID:1101360242458565Subject:Inorganic Chemistry
Abstract/Summary:PDF Full Text Request
By conventional method in water solution, new sixteen polyoxometalates based on polytungstates and transition metal complexes were synthesized. These compounds were further characterized by IR, UV-vis, single crystal X-ray diffraction. The preliminary thermal stability, magnetic and electrochemical properties were also investigated. The results are as follows:1. Six new compounds were synthesized and characterized. They were formed trilacunary Keggin type tungstobismuthates anions coordinated by the transition metal ions or transition metal complexes. Na18{Cu(im)4(H2O)2}3{Cu(im)4(H2O)}2[{Na(H2O)2}3{Cu4(im)6(H2O)}(BiW9O33)2]4·85H2O (1) Na2H8{Cu(im)4(H2O)}2[{Na(H2O)2}3-{Cu4(im)7}(BiW9O33)2]2·16H2O (2) Na8H[{Na(H2O)}3{Mn(im)}3(BiW9O33)2]·32H2O (3) Na9[{Na(H2O)2}3{Co(1-Meim)}3(BiW9O33)2]·36H2O (4) Na7H2[{Na(H2O)2}3{Mn(1-Meim)}3(BiW9O33)2]·21H2O (5) Na12[Co(H2O)2(OH)2{Bi2W22O74(OH)2}]·48H2O (6)Compounds 1 to 5 contain trilacunary [α-B-BiW9O33]9- subunits. Compound 1 shows an infinite chain structure by connection of {Cu(im)4} cation and sandwich type [{Na(H2O)2}3{Cu3(im)2(H2O)}(BiW9O33)2]9- polyanions. Compound 2 features a sandwich type polyanion [{Na(H2O)2}3{Cu4(im)7}(BiW9O33)2]5- monosupported by a {Cu(im)4} cation. Compounds 3 to 5 are all sandwich-type complexes in which two trilacunary [α-B-BiW9O33]9- anions are connected by alternate three Na+ and three transition metal ions. All the water molecules in the sandwich belt are substituted by imidazole molecules. Compound 6 contains a sandwich type [Bi2W22O74(OH)2]12- polyanion linked by Co2+ ions to form 1D chains. Magnetic properties of 1 to 5 indicate their antiferromagnetic interactions. As mono-nuclear cobalt containing complex, compound 6 indicated the effect of spin-orbital coupling on magnetism.2. Four new compounds were synthesized and characterized, which were formed by trilacunary [α-B-SbW9O33]9- anions modified by transitional metal complexes. Na18{Cu(im)4(H2O)2}3{Cu(im)4(H2O)}2[{Na(H2O)2}3{Cu4(im)6(H2O)}(SbW9O33)2]4·80H2O (7), Na9[{Na(H2O)2}3{Co(1-Meim)}3(SbW9O33)2]·41H2O (8) Na9[{Na(H2O)2}3{Mn(1-Meim)}3(SbW9O33)2]·41H2O (9) Na9[{Na(H2O)2}3{Ni(1-Meim)}3(SbW9O33)2]·30H2O (10) Compound 7 is isostructural to 1, in which the chains are constructed from {Cu(im)4} linkers and sandwich type polyanions. Compound 8 to 10 present sandwich type structures containing two trilacunary [α-B-SbW9O33]9- anions, in which the sandwich belt were filled with alternate three Na+ and three M2+ (M=Co2+, Mn2+, Ni2+) ions. The water molecules belonging to M2+ ions were substituted by 1-methylimidazole molecules. Magnetic properties of four compounds indicate antiferromagnetic interactions arising from the trinuclear transition metal (Cu2+, Co2+, Mn2+, and Ni2+) clusters.3. By participation of organic ligands and self-assembly in solution, two sandwich type compounds were isolated with tungstate and transition metal salt as starting materials. Na10H6[Mn4(H2O)2(α–MnW9O34)2]·31H2O (11) Na10H6[Co4(H2O)2(α–CoW9O34)2]·30H2O (12)Compounds 11 and 12 are isostructural and display sandwich type structures containing transition metal ions. The polyanions of the two compounds are constructed by [α-XW9O34]12- subunits linked through rhombus transition metal clusters. Magnetic property of compound 11 indicates an antiferromagnetic interaction between the Mn2+ ions. For compound 12, it shows an antiferromagnetic interaction.4. Four compounds were isolated and characterized with chain-like structures, which were formed by saturated dodecatungstates building blocks linked through copper complexes. Na4(OH)[{Cu2(EDTA)(H2O)2}{PW12O40}]·15H2O (13) Na4[{Cu2(EDTA)(H2O)2}{SiW12O40}]·17H2O (14) Na4H2[{Cu2(EDTA)(H2O)2}{H2W12O40}]·21H2O (15) Na6H2[{Cu(C2N2H8)2}{W12O42H2}]·36H2O (16)Compounds 13 to 15 display 1D chain structures based on saturated Keggin type polyanions building blocks linked by Cu-EDTA complexes. Theses chains are further linked by sodium clusters to form 2D layered network. The anionic chain in Compound 16 is formed by paradodecatungstates-B and bridging Cu-ethylenediamine complexes. Magnetic properties investigations indicated that there exist ferromagnetic interactions for compounds 13 to 15, while compound 16 indicated paramagnetic behavior. The successful syntheses of these compounds indicate that the hybrid materials with interesting topology and excellent properties can be realized by the rational choice of organic ligands.
Keywords/Search Tags:Trilacunary Keggin Structure, Polytungstate, Transition Metal, Crystal Structure, Magnetism
PDF Full Text Request
Related items