<p> A series of chiral transition metal clusters of the type MCo2(CO)6C-CO2R, where M = Co(CO)3, (C5H5)Mo(CO)2, (i-Pr-C5H4)Mo(CO)2 or (indenyl)Mo(CO)2 and R =menthyl or exo-bornyl have been synthesized and characterized using FAB mass spectrometry and high field NMR techniques. The isopropyl Cp and the indenyl ligands served as NMR probes to detect the chirality created by the incorporation of the terpenoidal capping group.</p> <p> The tricobalt clusters were treated with the bidentate ligands arphos, Ph2AsCH2CH2PPh2 and diphos, Ph2PCH2CH2PPh2. Treatment with arphos yields a pair of diastereomers which are interconverted via the migration of the Ph2As terminus of the arphos ligand from one cobalt vertex to another. This fluxionality was monitored by variable-temperature 31P NMR spectroscopy. The diphos cluster is not a fluxional molecule. However, the Co(CO)2P vertices are diastereotopic and give two signals in the 31P NMR. Thus, diphos serves as a convenient probe for chirality. </p> <p> In the case where M = Co(CO)3 , the two remaining cobalt vertices are diatereotopic and are, in principle, not equally susceptible to attack by an incoming ligand. To test for chiral discrimination, these molecules have been treated with several different phosphines. If the reaction were to proceed with any degree of selectivity, the 31P NMR spectrum ought to show resonances of unequal intensity. Such results have been obtained when a bulky phosphine, such as tricyclohexylphosphine, has been employed.</p> / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/19180 |
| Date | 08 1900 |
| Creators | Clark, Debbie Tania |
| Contributors | McGlinchey, M. J., Chemistry |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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