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Title: The importance of transition metals in supraicosahedral heteroboranes
Author: Lopez Pascual, Maria Elena
ISNI:       0000 0001 3612 7044
Awarding Body: Heriot-Watt University
Current Institution: Heriot-Watt University
Date of Award: 2007
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This thesis describes the synthesis and characterisation of icosahedral and mainly supraicosahedral metallacarboranes. Common late transition metal fragments are used . for metallation of the carborane cage and the consequences on the structure and behaviour of the molecules are discussed. Chapter 1 gIves a background to carborane and metallacarborane chemistry, providing the reader with an overview of the pertinent literature related to the work presented in this thesis. The polyhedral expansion route to metallacarboranes features heavily, since the main aspect ofthis thesis is the investigation of the role of transition metals in supraicosahedral heterobor~nes. Chapter 2 describes the syntheses and characterisations of icosahedral metallacarboranes followed by a discussion ofhow the replacement of a {BH} vertex with {ML} leads to significant changes in the molecular structure and spectroscopic . properties of these molecules. Chapter 3 reports the preparation of a range of 13-vertex bimetallacarboranes by supraicosahedral expimsion of icosahedral metallacarboranes, accompanied by a , discussion of the structural differences found between these Wadian species and non- Wadian analogues reported ·in the literature. A proposed mechanism for the isomerisation ofnido m~tallacarboranes is also reported. Chapter 4 presents a new isomer of 13-vertex monometallacarboranes 4,1,10MC2BlO, followed by its thermal isomerisation to the more thermodynamically stable ..4,1,12- analogue, constituting an improved route to the synthesis of this isomer. Chapter 5 details the synthesis and crystallographic characterisation of 14-vertex . bimetallacarboranes. These molecules have been predicted to adopt a bicapped 'hexagonal antiprismatic structure with the metal atoms occupying the high-connected ,positions; however, the first exception to this trend will be presented. Chapter 6 focuses on electrochemical studies of series of 12- and 13-vertex metallacarboranes. Since the polyhedral expansion of metallacarboranes involves the ·tia1 reduction of a closo species, it is mandatory to investigate the electrochemical properties of these molecules, as well as the different methodologies to modulate their redox potentials. Chapter 7 reports experimental details of the syntheses and characterisation of all the -above compounds. Appendices 1 and 2 list the crystallographic data along with details of the structure solution and refinement.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available