Convenient synthesis of tris-heteroleptic ruthenium(II) polypyridyl complexes

A convenient synthesis of tris-heteroleptic polypyridyl [Ru(pp)(pp')(pp ")](2+) complexes is reported (where pp, pp', and pp " represent three different polypyridyl ligands). Photolysis of [BzRu(pp)CI]Cl (Bz = eta (6)-C6H6) gives a mixture of Ru(pp)(CH3CN)(2)Cl-2 and [Ru(pp)(CH3CN)(3)Cl]Cl. Refluxing this mixture with pp' yields Ru(PP)(pp')Cl-2. Finally, refluxing Ru(pp)(pp')Cl-2 with pp " in a 75% ethanol/water solution gives [Ru(pp)(pp')(pp ")](2+). No ligand scrambling is observed. The complexes are characterized by H-1 NMR, elemental analysis, FAB-MB, UV-vis and emission spectroscopy, and cyclic voltammetry.