The synthesis and characterisation of novel rhodium(III) heteroleptic complexes
Burke, Helen M. (2003) The synthesis and characterisation of novel rhodium(III) heteroleptic complexes. PhD thesis, Dublin City University.
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It is the aim of the work that will be discussed in the following thesis to contribute to the field of Rh(III) polypyridyl chemistry. A series of heteroleptic Rh(III) polypyridyl complexes have been synthesised and characterised from the perspective of studying the effect of ligand variation and it was also hoped that it would be possible to develop dinuclear Ru(II)-Rh(III) complexes in which both the electron donor and the electron acceptor would be photoexcitable units.
A series of complexes of the form [Rh(L)2(L’)]n+ where L = bpy or phen, L’ = a pyridine triazole / pyrazine triazole/ triazine or imidazo based ligand and n = 2 or 3 have been synthesised and characterised. Chapter 3 focuses upon the synthesis, purification and structural characterisation of the complexes incorporating pyridine triazole ligands whereas Chapter 5 details the synthesis and structural characterisation of the complexes incorporating pyrazine, triazine, imidazole and triazole based ligands. Whilst particular emphasis was placed on the synthesis and structural characterisation of these complexes, their photophysical and electrochemical properties were also studied and Chapters 4 and 6 detail the results of these studies. The complexes all contain ligands with different adonor and 7t-acceptor properties and their characterisation aims to determine if the variation of these ligand properties influences their photophysical and electrochemical properties. Their behaviour is compared with that of the tris homoleptic complexes [Rh(phen)3]3+ and [Rh(bpy)3 ]3+ and where possible with analogous Ru(II) complexes. Chapter 7 details the numerous synthetic approaches which were taken in attempts to synthesise Rh(III)/Ru(II) dinuclear complexes and also discusses the difficulties which were encountered. Chapter 8 aims to take the results discussed throughout the thesis into consideration and discusses the issues of coordination modes, protonation states and the photophysical and electrochemical properties of all of the complexes synthesised, with particular emphasis being placed upon their behaviour in relation to their ligand adonor and 71-acceptor strengths. Having analysed the results obtained, Chapter 8 also proposes avenues through which this research can progress.
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