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Title: Ether carbaboranes and their metal complexes
Author: Shaw, Kenneth Forbes
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1992
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Chapter 1 describes the general area of carbaborane and carbametallaborane chemistry, with emphasis on characterisation and bonding, thus serving as an introduction to the work of the thesis. The chapter concludes with a brief description of the aims and scope of this work. Chapter 2 describes the synthesis and characterisation of ether carbaboranes, compounds in which one or both of the carbon atoms of a closo C2B10 or a nido C2B9 carbaborane cage are substituted with ether groups (such as -CH2OCH3). Emphasis is placed on the 11B n.m.r. properties of such compounds; the 11B n.m.r. spectra of several species are assigned (by 11B-11B COSY n.m.r. and the application of empirical rules), the relative order of the resonances for each species are rationalised, and the ether groups are found to act as electron withdrawing groups. Also studied are the crystal and molecular structures of 1-(CH2OCH3)-1,2-closo-C2B10H10, 2, [BTMA][7-CH2OCH3)-7,8-nido-C2B9H11], 5, and (thf)2Li[7,8-(CH2OCH3)2-7,8-nido-C2B9H10], 11. In 5, the ether group is above the open face of the carbaborane cage, such conformation being shown to be electronically/sterically preferred by the results of EHMO calculations. In 11, the two ether groups are coordinated to a lithium atom and both are above the open face of the carbaborane cage. Chapter 3 details studies on late d block metal complexes with ether carbaborane ligands, and again emphasis is placed on their 11B n.m.r. properties and their solid state structures. The crystal and molecular structures of 1,2-(CH2OCH3)2-30(p-cym)-3,1,2-closo-C2B9H9, 12, 1-(CH2OCH3)-3,3-(Me2PhP)2-3,1,2-pseudocloso-PtC2B9H10, 16, and α- and β-7,8-(CH2OCH3)2-10-endo-(Ph3PHg)-7,8-nido-C2B9H9, 17α and 17α, are described. In 12, which contains a d6(Ru) metal centre, the ether oxygen atoms are orientated away from the metal atom. In 16, which contains a d8(Pt) metal centre, one of the two molecules in the asymmetric fraction of the unit cell has the ether oxygen atom weakly coordinated to the platinum atom. Additionally, the 'rotation' of the (Me2PhP)2Pt group over the C2B3 face of the carbaborane cage is investigated using EHMO calculation, and found to be the result of the effect of the pendant ether group on the frontier MO's of the carbaborane. In both 17α and 17β, the mercury atom is coordinated by pendant ether groups; both in 17α, only one in 17β.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available