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Title: Synthesis and structural characterisation of carbametallaboranes of relevance to organometallic chemistry
Author: Douek, Natalia L.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1993
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Chapter 1 begins with a brief introduction to the structural characteristics of cyclopentadienyl complexes and carbametallaboranes derived from [7,8-nido-C2B9H11]2-. This is followed by a discussion of the chemistry of monoanionic nido-icosahedral carbaboranes, paying particular attention to compounds containing the ligand [9-SMe2-7,8-nido-C2B9H10]-. The chapter ends with a survey of compounds involving the sterically demanding species [7,8-Ph2-7,8-nido-C2B9H9]2-. Chapter 2 describes the synthesis and spectroscopic and structural characterisation of three [ML2] derivatives of [9-SMe2-7,8-nido-C2B9H10]-. The crystallographically observed cornformations of the [ML2] fragments with respect to the carbaborane ligand in 3,3-(CO)2-4-SMe2-4-SMe2-3,1,2-closo-RhC2B9H10, 1, and 3-(η2,η2-C8H12)-4-SMe2-3,1,2-closo-3,1,2-RhC2B9H10, 2, differ significantly from those adopted by (ML2) complexes of the unsubstituted ligand [7,8-nido-C2B9H11]2-. This has been traced to differences in the π frontier molecular orbitals of the carbaborane fragments, the observed orientations being consistent with the results of extended Hükel molecular orbital (EHMO) calculations. The conformation adopted in [3-(η2,η2-C_8H_12)-4-SMe_2-3,1,2-closo-PdC_2B_9H_10]BF_4, 4.BF_4, is strongly influenced by electrostatic interactions both within and between ion pairs within the crystal. 4^+ is a rare example of a cationic heteroborane, analogous to compound 2 except in the notional replacement of Rh^+ by Pd^2+ . Comparative EHMO calculations show that the additional charge in 4^+ is delocalised over the entire icosahedral framework and is not localised either at the metal vertex or at the pendant, cage-bound sulphur atom. Chapter 3 presents a series of palladium allyl derivatives of [9-SMe_2-7,8-nido-C_2B_9H_10]^- of the general formula 3-(C_3H_4R)-4-SMe_2-3,1,2-closoPdC_2B_9H_10, all of which have been characterised by ^1H and ^11B n.m.r. spectroscopy. and three of which have been structurally characterised.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available