Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.666227
Title: Structural (mis)behaviour in selected heteroboranes
Author: McGrath, Thomas David
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1994
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Abstract:
This Thesis deals with some aspects of the unusual structural behaviour observed in certain polyhedral heteroboranes. Chapter 1 begins with an overview of the recent development of polyhedral boron hydride chemistry, and an illustration of the present scope and utility of the field. Some appropriate aspects of the nomenclature of these species are then presented, followed by a brief survey of electron counting rules and bonding approaches. The preparative chemistry of carbaboranes is introduced, and features of the structural behaviour of C-phenyl carbaboranes are discussed in particular; a short illustrative review of some chemistry (primarily synthesis) of other heteroboranes then ensues. Thereafter, there is a discussion of boron clusters containing metal vertices. The Chapter then proceeds to a consideration of a number of aspects of heteroborane structural behaviour - namely cluster distortion, isomerisation and anomalous geometries - and concludes with an indication of the scope of work in the next Chapters. In Chapter 2 are presented the syntheses and characterisation of the species 1-Ph-2-R-1,2-closo-C2B10H10 (R = Me, 1; Br, 2; Me3Si, 3; tBuMe2Si, 4; iPr3Si, 5); compounds 1 to 4 were the subject of single crystal X-ray diffraction studies. An increasing steric interaction between the Ccage-bound substituents is apparent, and gives rise to mutual bending back of the pendant groups in addition to forcing a progressive elongation of the Ccage-Ccage connectivity. Internal distortions of the somewhat flexible trialkylsilyl substituents further relieve the intramolecular crowding. The sterically-induced distortions of the carbaborane polyhedron are analysed in detail, and evidence is presented which discounts movement along a diamond-square-diamond pathway; instead the results show that rotation of a Ccage-B(3 or 6) edge occurs, by pivoting of the appropriate triangular face.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.666227  DOI: Not available
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