Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.652003
Title: Mono- and dianionic carbaborane ligands and their transition metal complexes
Author: Hamilton, Ewan J. M.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1990
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Abstract:
Chapter 1 consists of a brief overview of transition metal cyclopentadienyl chemistry and of the chemistry of carbametallaborane species derived from [7,8-nido-C2B9H11]2-, with specific reference to the bonding modes commonly adopted by each ligand to transition metal fragments. The forms of the π-MO's of [C_5H_5]^-, [C_2B_9H_11]^2- and of the monoanionic ligand [9-SMe_2-7,8-C_2B_9H_10]^- (or [carb']^-), as obtained by extended Huckel molecular orbital (EHMO) calculations, are also presented. In Chapter 2, the structure of [7,8-C_2B_9H_12]^-, (1), is presented, showing an endo -H atom, rather than the commonly accepted μ-H, associated with the open ligand face. This result is supported by those of n.m.r. and theoretical studies. Isolobal replacement of the endo-terminal hydrogen atom by a (PPh3Au+ ) fragment leads to complex (2), [10-endo-(PPh3Au)-7,8-nido-C2B9H11]-, which has also been studied crystallographically. Structural trends within the series (1), (2) and [PPh3 Cu(C2B9H11)]- have been rationalised via the results of EHMO calculations. Chapter 3 presents the structure of [10,11-μ-H-9-SMe_2-7,8-nido-C_2B_9H_10], (3), the protonated precursor to the monoanionic ligand [carb']^-. The molecule possesses an asymmetric bridging H atom on its open face, a structural feature whose origin may be traced using MO calculations at the extended Huckel level. The (triphenylphosphine)gold(I) and (triphenylphosphine)copper(I) derivatives of [carb']^-, (4) and (5), have been prepared, and their structures determined by X-ray methods. In all three compounds, the SMe_2 substituent appears to adopt a preferred conformation, and it is suggested that this is allied to an intramolecular electrostatic interaction. Analysis of structural patterns within (3), (4) and (5) reveals different trends to those observed for the related series in the previous chapter. These differences may be rationalised by frontier MO considerations.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.652003  DOI: Not available
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