Polynuclear Transition Metal-Oxo Complexes Stabilized by Heteropolytungstates

  • Polyoxometalates (POMs) are a remarkable class of inorganic compounds with enormous structural and compositional diversity and potential applications in various fields such as catalysis, analytical chemistry, magnetism, nanotechnology, and medicine. My doctoral work is mainly concerned with incorporation of multinuclear transition metal complexes in polyoxometalate frameworks. In the course of this work we were able to develop a novel, simple and one-pot synthetic strategy for the preparation of high-nuclearity, transition metal-containing POMs. We have now succeeded in preparing several novel paramagnetic and diamagnetic metal substituted polyoxoanions in simple one-pot reactions and structurally characterized in detail using analytical methods like FT-IR, single crystal XRD, powder XRD, multinuclear NMR (1H, 13C,89Y 183W), elemental analysis and thermal analysis (TGA-DTA). We were able to synthesized MnII-containing polyanions [Mn19(OH)12(SiW10O37)6]34- (1), [{Mn(H2O)3}2{Mn2(a-GeW10O38)}3]20- (2), and [{Mn3(B-β-PW9O33(OH))(B-β-PW8O29(OH)2)}2]22- (3). Polyanion 1 represents the highest nuclearity manganese-containing POM to date. The synthesized 16-CoII-containing [{Co4(OH)3PO4}4(A-α-PW9O34)4]28- (8) also represents the largest cobalt aggregate in polyoxotungstate chemistry, and the first example of a POM-based cobalt-core possessing single molecule magnetic behavior. The tetrameric 14-NiII-containing [(Ni14(H2O)10(OH)6(PO3(OH))4(α-P2W15O56)4]34- (5) represents the largest nickel aggregate in polyoxotungstate chemistry. The asymmetric 5-NiII-containing [Ni5(H2O)4(OH)4(b-GeW9O34)(b-GeW8O31)]14- (6) and the dimeric, sandwich-type polyanion [(NaOH2)2Ni2(P2W15O56)2]18- (7) were also isolated. The synthesized 15-CuII-containing [(A-a-SiW9O34)4Cu15O4(OH)8Cl]27- (8) represents the polyanion with the second largest copper-oxo-hydroxo core. The YIII-containing polyanions [{Y(H2O)(B-a-H2SbW9O33)}3(CH3COO)3(WO4)]17- (9a) and [{Y(H2O)3}8(As2W19O68)3(As2W19O66)(W2O6)2(WO6)]43- (10) have also been synthesized and structurally characterized. The solid-state frameworks, composed of cocrystallized trinuclear ruthenium cations and polyanions were also synthesized. These materials exhibit nanosized voids filled with crystal waters. These water molecules can be removed reversibly upon heating under a vacuum, and powder XRD measurements demonstrated that the crystallinity of the compound was preserved. Sorption studies on ethanol and methanol were also performed.

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Publishing Institution:IRC-Library, Information Resource Center der Jacobs University Bremen
Granting Institution:Jacobs Univ.
Author:Masooma Ibrahim
Referee:Ulrich Kortz, Gerd-Volker Röschenthaler, John Errington
Advisor:Ulrich Kortz
Persistent Identifier (URN):urn:nbn:de:101:1-2013052812474
Document Type:PhD Thesis
Date of Successful Oral Defense:2011/03/04
Date of First Publication:2011/04/11
PhD Degree:Chemistry
School:SES School of Engineering and Science
Other Countries Involved:United Kingdom
Library of Congress Classification:Q Science / QD Chemistry / QD450-801 Physical and theoretical chemistry / QD474 Complex compounds
Call No:Thesis 2011/09

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