The redox chemistry of dimetal paddlewheel complexes bridged by guanidinate anions and a structural study of triboluminescence /
This dissertation consists of two independent topics: (1) the redox chemistry of dimetal paddlewheel complexes bridged by guanidinate anions, with M = W, Os, Re, Cr; (2) a structural study of triboluminescence (abbreviated as TL). On the first topic, W₂(hpp)₄, [Os₂(hpp)₄Cl₂]PF₆, [Re₂(hpp)₄]Cl₂]PF...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2002.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=765069761&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | This dissertation consists of two independent topics: (1) the redox chemistry of dimetal paddlewheel complexes bridged by guanidinate anions, with M = W, Os, Re, Cr; (2) a structural study of triboluminescence (abbreviated as TL). On the first topic, W₂(hpp)₄, [Os₂(hpp)₄Cl₂]PF₆, [Re₂(hpp)₄]Cl₂]PF₆ and [Cr₂(DPPC)₄]PF₆ were synthesized and characterized using X-ray diffraction and other physical methods. W₂(hpp)₄ is extremely electron rich and can be a strong two-electron reducing agent. [Os₂(hpp)₄Cl₂]PF₆ is the first compound which contains a M₂⁷⁺ core in several thousand dimetal paddlewheel complexes. Its interesting crystallographic features and magnetic properties are discussed. [Re₂(hpp)₄]Cl₂]PF₆ is the first compound that contains a Re₂⁷⁺ core. [Cr₂(DPPC)₄]PF₆ is the first dichromium complex that contains a Cr₂⁵⁺ core, a result further illustrates that guanidinate anions can stabilize the dimetal units with higher oxidation states. On the second topic, efforts were made to verify the validity of Zink's rule, which was proposed by Prof. J. I. Zink that if a crystal is triboluminescent, its crystal structure should be noncentrosymmetric. The structures of six tetrahedral Mn(II) complexes, out of 11 such complexes whose triboluminescence activities were known previously, were determined by X-ray diffraction. It was observed that in this set of compounds, none of them violates Zink's rule. The structure of (TEA)[Eu(DBM)₄], a repeatedly cited exception to Zink's rule, was refuted by a careful structure redetermination, and is not an authentic exception any more. But the structure redeterminations of three other claimed exceptions, namely (piperidinium)[Eu(BA)₄], [TbCl₂(H₂O)₆]Cl, and [Tb(antipyrine)₆]I₃, confirmed the literature results, so that these three are authentic exceptions to Zink's rule. It can be concluded that noncentrosymmetry is not a necessary condition to triboluminescence. A TL activity test of two noncentrosymetric crystals, Na₃[Eu(ODA)₃]·8H₂O and Eu₂Phen₂(C₈H₇O₂)₆·2H₂O were carried out. The negative results suggest that noncentrosymmetry is not a sufficient condition to triboluminescence either. In summary, the linkage between noncentrosymmetry and TL activity is weakened due to this study, quite contrary to what was originally expected. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xvi, 122 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 108-113). |