The Combination of 4-Hydroxythiazoles with Azaheterocycles: Efficient Bidentate Ligands for Novel Ruthenium Complexes

Herein the syntheses of three novel ligands, in which an azaheterocycle is connected with a thiazole subunit: 4-methoxy-5-methyl-2-pyridine-2-yl-1,3-thiazole (1), 4-methoxy-5-methyl-2-pyrimidine-2-yl-1,3-thiazole (2) and 4-methoxy-5-phenyl-2-pyridine-2-yl-1,3-thiazole (3) are reported. Because these ligands are cyclic versions of 1,4-diazadienes, they offer good prerequisites for the synthesis of metal complexes and were employed as chelating ligands. Three novel heteroleptic cationic complexes of the type Ru(bpy)(2)(L), with bpy 2,2'-bipyridine were successfully synthesised. The Ru-II complexes as well as the ligands were characterised by means of mass spectrometry, NMR, UV/Vis and IR spectroscopy and elemental analysis. Furthermore, an X-ray structure of Ru(bpy)(2)2(PF6), as far as we know the first example where a thiazole is directly connected to a Ru-II core, is presented in this paper.