The synthesis and characterisation of Rh(III) complexes with pyridyl triazole ligands

A series of Rh(III) mixed ligand polypyridine type complexes have been prepared. Complexes of the form [Rh(L)(2)(L)](n+), where n = 2/3 L = 2,2'-bipyridine (bpy)/1,10-phenanthroline (phen) and L' = 3-(pyridin-2-yl)-1,2,4-triazole (Hpytr), 1-methyl-3-(pyridin-2-yl)-1,2,.4-triazole (1M3pytr), 4-methyl-3-(pyridin-2-yl)-1,2,4-triazole (4Mpytr), 3,5-bis(pyridin-2-yl)-1,2,4-triazole (Hbpt), 4-amino-3,5-bis(pyridin-2-yl)-1,.2,4-triazole (NH(2)bpt) and 3-(pyridin-2-yl)-5-phenyl-1,2,4-triazole (HPhpytr), have been prepared and their synthesis and characterisation are reported. Crystals of [Rh(bpy)(2)(Phpytr)](PF6)(2) and [Rh(phen)(2)(NHbpt)](PF6)(2) were obtained and their structures determined. Analysis of X-ray crystallographic data showed that coordination of the metal centre in [Rh(phen)(2)(NHbpt)](PF6)(2) occurs via the amine moiety and a nitrogen of the pyridine ring. NMR studies illustrated that coordination to the NH(2)bpt ligand was also possible via a nitrogen of the triazole ring and the pyridine ring forming the complex [Rh(phen)(2)(NH(2)bpt)](PF6)(3). The absorption and emission properties of the complexes studied were found to be pi-pi* in nature and preliminary evidence suggests that all complexes with the exception of [Rh(phen)(2)(NHbpt)](PF6)(2) and [Rh(bpy)(2)(NHbpt)](PF6)(2) are dual emitting at 77 K. (C) 2004 Elsevier B.V. All rights reserved.