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Title: Unusual molecular structures of boron halides and carboranes : combining experiment and theory
Author: Mackie, Iain D.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2003
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This thesis is concerned with the determination of the structures of the polyboron fluorides B4F6CO, B8F12 and B10F12 and the carboranes closo-2,3-C2B9H11, nido-2,9-C2B9H13 and arachno-6,9-C2B8H14 by experiment and theoretical calculations. B8F12 is the first fully characterised higher boron fluoride and we can also report the second - B10F12. Its crystal structure contains a tetrahedron of boron atoms, each with a BF2 substituent, similar to the known B4X4 tetrahedra but with two additional BF2 bridge bonds. Ab initio calculations identify a very different structure. The molecule is based upon a folded B4 central core as in B8F12, but this core is highly symmetrical in B10F12. However, calculations involving sterically larger substituents such as in B10Cl12, B10Br12 and B10I12 show molecular structures as found in crystalline B10F12. Carboranes form a widely studied class of molecule but past structural studies have generally relied upon theoretical calculations or NMR spectroscopy whilst, due to a general inability to form single crystals, diffraction studies have been carried out on salts or derivatives of the parent cluster. To further the understanding of carborane cluster structures the compounds closo-2,3-C2B9H11, nido-2,9-C2B9H13 and arachno-6,9-C2B8H14 have been experimentally characterised using gas-phase electron diffraction; they show structures comparable to known carboranes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available