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Research Projects I |
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BACKGROUND Throughout the world, complexes of d6-metal centres, such as RuII, ReI, and RhIII are the focus of much research. This is because complexes based on these species are electrochemically active and their photoexcited states can luminesce or function as strong oxidising/reducing agents. However, most of the work in this area is based on nitrogen-donor ligands such as ammines or pyridines.
The Thomas group is exploring the properties of RuII systems that contain S-donor macrocyclic ligands, known as thiacrowns.[1] Due to their coordination behaviour and physical properties thiacrowns can be used to tune the chemistry and electronics of the metal units used in such systems.[2] WHY? Such systems answer fundamental questions concerning electron transfer, a process that is essential for biological processes such as photosynthesis and cellular metabolism. These complexes can also form prototypes for nanotechnological devices such as molecular wires
For these reasons, the Electron-Transfer, ET, processes of dinuclear thiacrown complexes are of particularly interest.[1-3] For example, in the mixed-valence (RuIII/II) state of the dinuclear complexes shown below, an electron is completely delocalised between the two ruthenium centres (in pink) in the system to the left, but in the system to the right a localised electron hops between the two ruthenium centres.[3] |
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X-ray Crystal structures of two dinuclear RuII thiacrown complexes
COLLABORATIONS ON THIS PROJECT: In collaboration with Prof. Mike Ward (University of Sheffield) more complicated systems with redox active bridging ligands are currently being developed. While Prof. Vitor Felix (University of Aveiro, Portugal) is carrying out detailed computational studies (DFT) on the electronic properties of these complexes. |
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1. Thiacrown complexes of d6-metal centres. |
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Frontier orbitals of mononuclear Ru(II) complex [DFT calculations and image by Vitor Felix, Aveiro Portugal] |
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REFERENCES 1. “[RuII([9]-ane-S3] - a versatile building block for coordination chemistry,” J. A. Thomas, Eur. J. Inorg Chem, invited review in preparation. 2. “RuII Electron Transfer Systems Containing S-donor Ligands,” C. S. Araújo, M. G. B. Drew. V. Félix, L. Jack, J. Madureira, M. Newell, S. Roche, T. M. Santos, J. A. Thomas, L. Yellowlees, Inorg. Chem., 2002, 41, 2250; “Ru(II) Complexes Incorporating Tetrathia-macrocycles: Synthesis and Conformational Analysis,” H. Adams, A. M. Amado, V. Félix, B. E. Mann, J. Antelo-Martinez, M. Newell, P. J. A. Ribeiro-Claro, S. E. Spey, J. A. Thomas, Chem., Eur. J., 2005, 11, 2031 - 2046. 3. “Electrochemical properties of dinuclear [Ru([n]-ane-S4] complexes of 2,3-bis(2-pyridyl)pyrazine,” M. Newell, J. A. Thomas, Dalton Trans, 2006, 705 - 709 4. .“Structure and Properties of Dinuclear [RuII([n]aneS4) Complexes of 3,6-bis(2-pyridyl)-1,2,4,5- tetrazine,” M. Newell, J. D. Ingram, T. L. Easun, S. J. Vickers, M. D. Ward, J. A. Thomas, Inorg. Chem.,2006, 45, 821 - 827 . |
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Research Projects I |
