Structure and reactivity of group 6 metal carbonyls stabilized by pi-donating ligands /
The fluoride ion is a cis-labilizing agent towards the group 6 metal carbonyls. The labilizing ability is seen from reactivity studies monitored by infrared and NMR spectroscopies and by the isolation and x-ray crystal structure of [Et4N]3[W2(CO)6F3]. This complex decomposes over time into the str...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1995.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=742744411&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The fluoride ion is a cis-labilizing agent towards the group 6 metal carbonyls. The labilizing ability is seen from reactivity studies monitored by infrared and NMR spectroscopies and by the isolation and x-ray crystal structure of [Et4N]3[W2(CO)6F3]. This complex decomposes over time into the structurally characterized [Et4N]2[WF6]-Only in the presence of CO can the pentacarbonyl fluoride be observed. The methoxide ion is also a strong cis-labilizer, forming dinuclear tetracarbonyl, dinuclear tricarbonyl, or tetranuclear tricarbonyl clusters. The systematic synthesis of all three types of clusters has been elucidated. The crystal structures of [Et4N]2[W(CO)4OMe]2 and [Et4N]4[W(CO)3OMe)14 have been determined. Doubly deprotonated catechol has been used to stabilize chromium tricarbonyl as a coordinatively unsaturated species satisfied by the R-donation of the catecholate. The crystal structure of this species both with and without a hydrogen-bound catechol have been determined. The reactivity of this species towards incoming ligands has been studied with the hydrogen-bound species found to be more reactive. 3,5-Di-tert-butylcatecholate has been employed for the stabilization of unsaturated group 6 metal carbonyls. The stabilization of the unsaturated coordination sphere was found to increase in the order W < Mo < Cr. For tungsten, x-ray crystal structure determinations were conducted for both the tetracarbonyl and the tricarbonyl. The saturated tetracarbonyl is not isolable for molybdenum and chromium. Crystal structures were obtained for the tricarbonyl molybdenum and chromium derivatives. The interaction of deprotonated amine ligands with the group 6 was studied. The successful synthesis of [Et4N]2[W(CO)3OC6H4NHI and [Et4N]2[W(CO)3N(H)C6H4NHI demonstrates that ligands containing amido groups are able to stabilize unsaturated metal centers. The x-ray crystal structures of these complexes show that the more donating ligand occupies an equatorial site in the distorted trigonal bipyramidal geometry. This result is in agreement with that found for the 3,5-di-tert-butylcatecholate analog. |
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| Item Description: | Vita. "Major Subject: Chemistry". In title, symbol for Greek letter pi is used. |
| Physical Description: | xi, 146 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references. |