The electronic and solvatochromic properties of [Co(L)(bipyridine)2]+ (L = o-catecholato, o-benzenedithiolato) species: a combined experimental and computational study

Cioncoloni, G., Senn, H. M. , Sproules, S. , Wilson, C. and Symes, M. (2016) The electronic and solvatochromic properties of [Co(L)(bipyridine)2]+ (L = o-catecholato, o-benzenedithiolato) species: a combined experimental and computational study. Dalton Transactions, 45(39), pp. 15575-15585. (doi: 10.1039/C6DT02807A)

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Complexes of Co(III) containing mixed chelating diimine and o-quinone ligand sets are of fundamental interest on account of their fascinating magnetic and electronic properties. Whilst complexes of this type containing one diimine and two o-quinone ligands have been studied extensively, those with the reverse stoichiometry (two diimines and one o-quinone) are much rarer. Herein, we describe a ready route to the synthesis of the complex [CoIII(o-catecholate) (2,2′-bipyridine)2]+ (1), and also report the synthesis of [CoIII(o-catecholate)(5,5′-dimethyl-2,2′-bipyridine)2]+ (2) and [CoIII(o-benezenedithiolate)(5,5′-dimethyl-2,2′-bipyridine)2]+ (3) for the first time. Spectroscopic studies show that complex 2 displays intriguing solvatochromic behaviour as a function of solvent hydrogen bond donation ability, a property of this type of complex which has hitherto not been reported. Time-dependent density function theory (TD-DFT) shows that this effect arises as a result of hydrogen bonding between the solvent and the oxygen atoms of the catecholate ligand. In contrast, the sulfur atoms in the benzenedithiolate analogue 3 are much weaker acceptors of hydrogen bonds from the solvent, meaning that complex 3 is only very weakly solvatochromic. Finally, we show that complex 2 has some potential as a molecular probe that can report on the composition of mixed solvent systems as a function of its absorbance spectrum.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Sproules, Dr Stephen and Cioncoloni, Giacomo and Wilson, Dr Claire and Senn, Dr Hans and Symes, Professor Mark
Authors: Cioncoloni, G., Senn, H. M., Sproules, S., Wilson, C., and Symes, M.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Dalton Transactions
Publisher:Royal Society of Chemistry
ISSN (Online):1477-9234
Published Online:08 September 2016
Copyright Holders:Copyright © 2016 Royal Society of Chemistry
First Published:First published in Dalton Transactions 45(39):15575-15585
Publisher Policy:Reproduced under a Creative Commons License
Data DOI:10.5525/gla.researchdata.350

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