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 Lam bda Lambda', Lambda Lambda Delta', Delta Lambda Delta' and Delta Lambd a 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'-bi pyridine), and the diastereoisomeric forms of the heteroleptic homomet allic trinuclear species u(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 met al attached to the ligands bpy, phen and dmbpy, respectively) have bee n isolated using a combination of stereoselective syntheses and chroma tographic procedures. In both cases dinuclear species with predetermin ed stereochemistry were used as precursors: the various stereoisomers of the target trinuclear species were characterised on the basis of th e known stereochemical course of the synthetic reactions, in combinati on with NMR and CD spectroscopy.