CH/π Interaction in Linkage Isomers of Bis(2,2′-bipyridine)ruthenium(II) Complexes with Pyrimidine-2-thione and Related Ligands

Ruthenium(II) complexes containing nine pyrimidine-2-thione [Ru(L-N,S)(bpy)2]+ (HL = pyrimidine-2-thione; bpy = 2,2′-bipyridine) are prepared and characterized. Two linkage isomers exist for most of the complexes with unsymmetrical ligands. The isomeric ratios are interpreted by CH/π attractive interaction between the 4- or 6-alkyl group of the thione ligands and the π-system of bpy.