Investigation of CO-lability and CO2 insertion chemistry involving low valent group six metal carbonyl complexes containing []-donating amido, pseudoamido, or fluoride ligands /
The synthesis of a series of pseudoamido complexes of group six metal carbonyls has been accomplished in good yield. These complexes have been characterized by infrared, ¹³C NMR, elemental analysis, and X-ray crystallography. The []-donor ability of the pseudoamido group has been probed via ¹³CO exc...
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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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| Summary: | The synthesis of a series of pseudoamido complexes of group six metal carbonyls has been accomplished in good yield. These complexes have been characterized by infrared, ¹³C NMR, elemental analysis, and X-ray crystallography. The []-donor ability of the pseudoamido group has been probed via ¹³CO exchange kinetics. Examined herein are also amido and fluoride complexes of tungsten(0) carbonyls. The amido complexes have been examined for reactivity with CO₂, and the insertion chemistry explored, both experimentally and computationally. A series of group six metal carbonyl complexes with uracilate lipids has been synthesized and characterized. X-ray crystallography has shown that these complexes may bind via N1, N3, or exocyclic sulfur depending on the uracil derivative used. ¹³CO exchange kinetics has lead to information related to the a-donor ability of the pseudoamido group. The kinetics and mechanism of CO loss lead to a tetracarbonyl complex with a N-S chelated thiouracilate. Also investigated was the reverse process of CO addition to the tetracarbonyl complex leading to the parent pentacarbonyl S-bound thiouracilate complex. Ab initio calculations were used in the examination of the CO dissociation/addition reaction. A series of sixteen electron coordinatively unsaturated group six metal carbonyls and their eighteen electron analogues have been examined here using HF and DFT calculations. The calculations have been used to draw conclusions regarding the relative stability of the sixteen vs. eighteen electron complexes. The synthesis of W(CO)₄(2-amidopyridine)-, [Na]₂[W(CO)₄(2-amidopyridine)]₂, and [Na][W(CO)₅(2-amidopyridine)]has been accomplished in moderate yield. The CO₂ insertion chemistry was examined for these complexes via IR, NMR, as well as theoretical calculations, and it was found that only W(CO)₄(2-amidopyridine)- exhibited insertion of CO₂ into the W-N bond. Recent results on the synthesis and characterization of tungsten(0) carbonyl complexes with fluoride and amide lizards are discussed. These complexes are shown to be extremely good []-donor lizards and unstable due to CO loss and formation of dimeric products. The use of phosphates to stabilize the complexes as well as the synthesis of complexes resulting from the direct reaction of the amide ligand or fluoride with M(CO)₆ is discussed, where M = Cr or W. |
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| Item Description: | Vita. "Major Subject: Chemistry". In title symbols are used. |
| Physical Description: | xiv, 169 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 155-160). |