The synthesis and characterization of halide supported octahedral and pyramidal clusters of zirconium /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1993.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=744947541&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Abstract: | This dissertation presents the synthesis and characterization of ten clusters containing the $ rm Zr sb6X sb{12}$ core. The clusters were structurally characterized and found to span two general compositions, ($ rm Zr sb6X sb{12} sp{2+} rbrack X sb2(PR sb3) sb4$ (X = Cl or Br; R = alkyl) and ($ rm Zr sb6X sb{12} sp{n+} rbrack L sb6$ (n = 0, 2 or 3; X = Cl or Br; L = X or PR$ sb3).$ The Zr-Zr bond lengths have a range of 3.223-3.440 A, with the shorter and longer distances found in the more reduced ($ rm Zr sb6X sb{12}$) and oxidized ($ rm Zr sb6X sb{12} sp{3+}$) cores, respectively. Each of the ($ rm Zr sb6X sb{12} sp{2+} rbrack X sb2(PR sb3) sb4$ clusters has a small tetragonal distortion of the Zr$ sb6$ octahedron ($ rm O sb{h} to D sb{4h})$ arising from the disparate electron donor ability of the terminal ligands. The ($ rm Zr sb6X sb{12} sp{n+} rbrack L sb6$ clusters have effectively octahedral symmetry. The clusters were obtained by reduction of ZrX$ sb4$ with HSn(n-Bu)$ sb3$ and addition of phosphine or halide ligands. The presence of hydrogen atoms on, or in, the Zr$ sb6$ cores of the ($ rm Zr sb6X sb{12} sp{2+} rbrack X sb2(PR sb3) sb4$ and ($ rm Zr sb6X sb{12} sp{3+} rbrack X sb6$ clusters is supported by nuclear magnetic resonance (NMR) and mass spectroscopy data. We have also found that under slightly less reducing conditions, within a similar reaction scheme, pyramidal clusters of composition $ rm Zr sb5Cl sb{12}(PR sb3) sb5 (PR sb3 = PMe sb3, PEt sb3, PMe sb2Ph)$ can be obtained. Three clusters of this type were structurally characterized and in each case a significant distortion of the Zr$ sb5$ core was observed. The distortion is manifested in the basal plane where average Zr-Zr bond lengths of 3.475 A and 3.292 A exist. |
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| Item Description: | Vita. "Major subject: Chemistry." |
| Physical Description: | xvi, 202 leaves : illustrations ; 28 cm |
| Bibliography: | Includes bibliographical references. |