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

The stereoisomers (Delta Delta Delta', Delta Delta Lambda', Lambda Lambda Lambda', Lambda Lambda Delta', Delta Lambda Delta' and Delta Lambda Lambda'; the prime indicates the chirality of the osmium centre) of the heteronuclear trimetallic Ru2Os species [{Ru(bpy)(2)}(2){Os(bpy)(2)}{mu-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)}{mu-hat)](6+) (Delta(b) Delta(p) Delta(m)/Lambda(b) Lambda(p) Lambda(m), Delta(b) Delta(p) Lambda(m)/Lambda(b) Lambda(p) Lambda(m), Delta(b) Lambda(p) Delta(m)/ Lambda(b) Delta(p) Lambda(m), Delta(b) Lambda(p) Lambda(m)/Lambda(b) Delta(p) Delta(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.