Efficient Access to 5‐Bromo‐ and 5,6‐Dibromophenanthroline Ligands

Abstract

Bromo‐functionalized precursor molecules are essential for generating desired target compounds through cross‐coupling reactions. Herein we show an improved synthetic route, feasible at low temperatures and affording high yields, to the ligands 5‐bromo‐1,10‐phenanthroline ( 1 ) and 5,6‐dibromo‐1,10‐phenanthroline ( 2 ). The corresponding ruthenium complexes, containing various equivalents of ligand 2 , are easily accessible in high yields, including the analogue of tris‐homoleptic [Ru(bpy) 3 ] 2+ (bpy = 2,2′‐bipyridine), [Ru( 2 ) 3 ] 2+ . X‐ray diffraction analyses have provided detailed information on the structures of the ligands and their corresponding metal complexes. An investigation of the electrochemical properties has provided detailed information on the 3 MLCT state localized on 2 . We show the conversion of heteroleptic ruthenium complexes of these ligands in Suzuki cross‐coupling reactions whereas the ligands did not undergo reaction under the same conditions.