Isolation of Geometric Isomers within Diastereoisomers of Dinuclear Ligand-Bridged Complexes of Ruthenium(II)

The individual diastereoisomeric forms [ meso (ΔΛ) and rac (ΔΔ and ΛΛ)] of the ligand-bridged dinuclear species [{Ru(phen)(Me 4 bpy)} 2 (μ-bpm)] 4+ [phen = 1,10-phenanthroline; Me 4 bpy = 4,4‘,5,5‘-tetramethyl-2,2‘-bipyridine; bpm = 2,2‘-bipyrimidine] have been synthesized using chiral forms of the precursors [Ru(phen)(Me 4 bpy)(bpm)] 2+ and [Ru(phen)(Me 4 bpy)(py) 2 ] 2+ . The cis and trans geometric isomers of both diastereoisomeric forms have been separated by cation exchange chromatography and characterized by NMR spectroscopy. We also report the first chiral resolutions of a heteroleptic tris(bidentate)ruthenium(II) complex, [Ru(phen)(Me 4 bpy)(bpm)] 2+, and a heteroleptic bis(bidentate)bis(pyridine)ruthenium(II) complex, [Ru(phen)(Me 4 bpy)(py) 2 ] 2+, in both cases using cation exchange chromatography.