Dinuclear transition metal complexes containing the bridging ligand 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinate /
The discovery of the unsupported quadruple bond in Re₂Cl₈²⁻ in 1963 was seen as a hallmark in transition meal chemistry, and has proved to be the doorway to a fascinating and fruitful new area of chemistry. The paddlewheel-type structure in which four bridging lizards are bound to two metal atoms is...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1999.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=733678591&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The discovery of the unsupported quadruple bond in Re₂Cl₈²⁻ in 1963 was seen as a hallmark in transition meal chemistry, and has proved to be the doorway to a fascinating and fruitful new area of chemistry. The paddlewheel-type structure in which four bridging lizards are bound to two metal atoms is ideal for studying metal-to-metal interactions in these multiply bonded bimetal complexes because it maximizes possible d-orbital overlap between the two metals. Although a variety of bridging bidentate lizards promote the formation and stabilization of metal-to-metal multiple bonds in complexes of this type, it is clear that the bridging lizards do not, in general, force interaction of the metal centers. Presented here is the bulk of work completed on an in depth exploration of the bridging capabilities of l,3,4,6,7,8-Hexahydro-2H-pyrimido[1,2-a]pyrimidine (abbreviated Hhpp; the anionic form is denoted by hpp). Complexes of bimetal units containing molybdenum, chromium, vanadium, osmium and rhenium atoms prove that hpp is useful in many of the same ways as the amidinates. However, the first hint of the enhanced capabilities of hpp was seen in the isolation of the first Mo₂⁶⁺ complex of this type. The ability to stabilize a variety of oxidation states of the M₂[] core remains one of the most interesting aspects of hpp. The successful isolation of the series of Mo₂[] (n = 4,5,6) and the never-before-seen single bond between trivalent palladium atoms stand as a testimony to the enhanced abilities of hpp over annihilates. Some very recent work with tungsten and iridium continues to expand the "sphere of influence'' of hpp. The synthesis, characterization and interesting aspects of the following complexes will be discussed: Mo₂(hpp)₄, 1; Cr₂(hpp)₄, 2; V₂(hpp)₄, 3; Mo₂(hpp)₄Cl, 4; [Mo₂(hpp)₄][BF₄]₂ 5; 0s₂(hpp)₄Cl₂, 6; Re₂(hpp)₄Cl₂, 7; Re₂(hpp)₃C₃l, 8; Pd₂(hpp)₄, 9 and Pd₂(hpp)₄Cl₂, 10. |
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| Item Description: | Vita. "Major Subject: Chemistry". In title numerals are used. |
| Physical Description: | ix, 78 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 60-62). |