Isolation of geometric isomers within diastereoisomers of dinuclear ligand-bridged complexes of ruthenium(II)

Abstract

The individual diastereoisomeric forms [meso (ΔΛ) and rac (ΔΔ and ΛΛ)] of the ligand-bridged dinuclear species [{Ru(phen)(Me₄bpy)}₂(μ-bpm)]⁴⁺ [phen = 1,10-phenanthroline; Me₄bpy = 4,4',5,5'-tetramethyl-2,2'-bipyridine; bpm = 2,2'-bipyrimidine] have been synthesized using chiral forms of the precursors [Ru(phen)(Me₄bpy)(bpm)]²⁺ and [Ru(phen)(Me₄bpy)(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)(Me₄bpy)(bpm)]²⁺, and a heteroleptic bis(bidentate)bis(pyridine)ruthenium(II) complex, [Ru(phen)(Me₄bpy)(py)₂]²⁺, in both cases using cation exchange chromatography.