An improved synthesis of 4-cyano-1,10-phenanthroline, 4,7-dicyano-1,10-phenanthroline and their bis(4,4′-di-tert-butyl-2,2′-bipyridine)ruthenium(II) complexes

Abstract

This report describes a new palladium catalyzed synthesis of 4-cyano-1,10-phenanthroline (nphen, 1), 4,7-dicyano-1,10-phenanthroline (dnphen, 2) and their corresponding ruthenium complexes. The two cationic complexes, [(tbbpy)2Ru(nphen)]2+3 and [(tbbpy)2Ru(dnphen)]2+4 (tbbpy=4,4′-di-tert-butyl-2,2′-bipyridine), were synthesized using an improved microwave procedure. All compounds were fully characterized, including the solid-state molecular structures of the complexes. The influence of 1 and 2 on the metal-to-ligand charge transfer (MLCT) transitions were studied and compared to the ruthenium(II) polypyridyl complexes containing the related 4,4′-dicyano-2,2′-bipyridine (dnbpy) and the non-functionalized 1,10-phenanthroline (phen) ligand.