title: The synthesis and unexpected solution chemistry of thermochromic carborane-containing osmium half-sandwich complexes.
abstract: The functionalisation of the 16-electron complex [Os(η(6)-p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-dithiolato)] (1) with a series of Lewis bases to give the 18-electron complexes of general formula [Os(η(6)-p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-dithiolato)(L)] (L = pyridine (2), 4-dimethylaminopyridine (3), 4-cyanopyridine (4), 4-methoxypyridine (5), pyrazine (6), pyridazine (7), 4,4'-bipyridine (8) and triphenylphosphine (9)) is reported. All 18-electron complexes are in equilibrium in solution with the 16-electron precursor, and thermochromic properties are observed in some cases (2, 3, 5, 8, and 9). The binding constants and Gibbs free energies of the equilibria are determined using UV-visible titrations and their stabilities investigated. Synthetic routes for forcing the formation of the 18-electron species are proposed, and analytical methods to characterise the equilibria are described.
authors.affiliation: Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK. N.Barry@warwick.ac.uk.
authors.forename: Anaïs
authors.initials: A
authors.lastname: Pitto-Barry
authors.forename: Amy
authors.initials: A
authors.lastname: South
authors.forename: Alison
authors.initials: A
authors.lastname: Rodger
authors.forename: Nicolas P E
authors.initials: NP
authors.lastname: Barry