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Title: Structural and spectroscopic investigations of racemisation in C3-symmetric complexes
Author: McCormack, Chiara
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2005
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The study of ligands of the general formula [E(L2D)3] (E = bridgehead atom, L = linking atom, D = donor atom) was undertaken. Complexation of such ligands is of interest as it provides intrinsically chiral C3-symmetric complexes with both octahedral and tetrahedral metal centers. The possible exploitation of the chirality of C3-symmetric complexes of such ligands would be crucially dependant upon the energy barriers to their racemisation. To this end, complexes of the novel ligand hydrotris(2-mercapto-1-ethylimidazolyl)borate (NaTmEt) and the previously synthesised hydrotris(2-mercapto-1-benzylimidazolyl)borate (NaTmBn) were synthesised and Variable Temperature NMR was employed to investigate the energy barrier to racemisation in a range of tetrahedral and octahedral complexes. The results from ab initio calculations on a number of structures were compared to the findings of the VT NMR calculations. The novel complexes [MnTm(CO)3], [RuTm(p-cym)]Cl, [RuTm{C6H5(CO)OEt}]Cl and [SnTmCl3] (Tm = hydrotris(methimazolyl)borate) were synthesised. [MnTm(CO)3] is the first example of a manganese complex of the Tm ligand. The isoelectronic but structurally different complexes [Ru{κ3-HB(mt)3}Cp] and [Ru{κ2-(μ-H)B(mt)3}Cp] (mt = methimazole) were also synthesised. Although a crystal structure of [Ru{κ2-(μ-H)B(mt)3}Cp] has not been obtained we suggest that the complex is coordinated in a bis-chelate fashion by two thione sulphur atoms of the tripodal Tm ligand, and the coordination sphere is completed by a Cp ring and one hydrogen atom which is involved in an agnostic B-HRu interaction.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available