Structural and photophysical characterisation of coordination and optical isomers of mononuclear ruthenium(II) polypyridyl 1,2,4-triazole complexes

The X-ray crystal structure of the N^2 isomers of the Ru(bipy)2 complexes of Hphpztr (1) and Hpztr (2), (bipy = 2,2ʹ-bipyridine, Hphpztr = 2-(5ʹ-phenyl-4ʹH-[1,2,4]triazol-3ʹ-yl)pyrazine and Hpztr = 2-(4ʹH-[1,2,4]triazol-3ʹ-yl)pyrazine) are reported. The molecular structure obtained for 2 demonstrates an interesting structural aspect in the sharing of a single proton between two molecular units. The isolation of the (delta) and (lambda) stereoisomers of 1 and [Ru(phen)2(pztr)]+(phen = 1,10-phenanthroline)(3) by semipreparative HPLC is also reported. The compounds obtained are characterised by electronic spectroscopy and particular attention is paid to the photophysical properties of and isomers of 1 and 3, in chiral enantiopure (delta) and (lambda) racemic solvents.