Trichloridothallium(III) Complexes with Bipyridine Derivatives: From Structure to Luminescence Properties.

Abstract

Several new thallium(iii) complexes, [Tl(4,4′-dmbpy)Cl3(DMSO)]·H2O (1), [Tl(4,4′-dtbpy)Cl3(DMSO)] (2), [Tl(5,5′-dmbpy)Cl3(DMSO)]·(5,5′-dmbpy) (3), and [Tl(6-mbpy)Cl3(DMSO)] (4) (4,4′-dmbpy = 4,4′-dimethyl-2,2′-bipyridine, 4,4′-dtbpy = 4,4′-ditert-butyl-2,2′-bipyridine, 5,5′-dmbpy = 5,5′-dimethyl-2,2′-bipyridine, and 6-mbpy = 6-methyl-2,2′-bipyridine) were prepared from the reaction of TlCl3 with the mentioned ligands in DMSO. The four complexes were fully characterised and their structures were determined by X-ray diffraction. These complexes have a bidendate nitrogenous ligand, a DMSO molecule, and three chloride anions (in the facial position) attached to a TlIII metal centre in a distorted octahedral environment. The stability of the complexes in DMSO is evident by a 203,205Tl–1H spin–spin coupling, determined by 1H NMR spectroscopy. Interestingly, six bond hydrogen–thallium coupling was observed with a coupling constant of 6JTlH = 20 Hz. The absorption and emission spectra of the complexes were investigated. These studies revealed that upon coordination to TlIII, the luminescent intensity is increased in comparison with the related unbound ligands.