Stereoisomers in heterometallic (Ru₂Os) and heteroleptic homometallic (RuRu'Ru") trinuclear complexes incorporating the bridging ligand hat (1,4,5,8,9,12-hexaazatriphenylene)

Abstract

The stereoisomers (ΔΔΔ', ΔΔΛ', ΛΛΛ', ΛΛΔ', ΔΛΔ' and ΔΛΛ'; the prime indicates the chirality of the osmium centre) of the heteronuclear trimetallic Ru₂Os species [{Ru(bpy)₂}₂{Os(bpy)₂}(µ-hat)]⁶⁺ (hat = 1,4,5,8,9,12-hexaazatriphenylene; bpy = 2,2'-bipyridine), and the diastereoisomeric forms of the heteroleptic homometallic trinuclear species [{Ru(bpy)₂}{Ru(phen)₂}{Ru(dmbpy)₂}(µ-hat)]⁶⁺ (Δ^bΔ^pΔ^m/Λ^bΛ^pΛ^m, Δ^bΔ^pΛ^m/Λ^bΛ^pΔ^m, Δ^bΛ^pΔ^m/Λ^bΔ^pΛ^m, Δ^bΛ^pΛ^m/Λ^bΔ^pΔ^m; phen = 1,10-phenanthroline, dmbpy = 4,4'-dimethyl-2,2'-bipyridine; b, p and m denote the chirality of the metal attached to the ligands bpy, phen and dmbpy, respectively) have been isolated using a combination of stereoselective syntheses and chromatographic procedures. In both cases dinuclear species with predetermined stereochemistry were used as precursors: the various stereoisomers of the target trinuclear species were characterised on the basis of the known stereochemical course of the synthetic reactions, in combination with NMR and CD spectroscopy.