ISOLATION OF ENANTIOMERS OF A RANGE OF TRIS(BIDENTATE)RUTHENIUM(II) SPECIES USING CHROMATOGRAPHIC RESOLUTION AND STEREORETENTIVE SYNTHETIC METHODS

A range of chiral building blocks of the type Delta- or Lambda-[Ru(pp) (2)(CO)(2)](2+) {pp = bidentate ligands bpy (2,2'-bipyridine), phen (1 ,10-phenanthroline) and Me(2)bpy (4,4'-dimethyl-2,2'-bipyridine)} have been synthesized, and their enantiomeric purity and absolute configur ations determined by CD and NMR studies. Decarbonylation using trimeth ylamine oxide in the presence of the respective pp Ligand at room temp erature produced the corresponding tris(bidentate) species [RU(pp)(3)] (2+) With retention of configuration at the ruthenium(II) centre. A ge neral chromatographic technique for resolution of tris-homoleptic comp lexes of the type [RU(pp)(3)](2+) was investigated, with the absolute configurations of the resolved complexes confirmed by CD studies, and the X-ray structural analyses of )-[Ru(Me(2)bpy)(3)]{(-)-O,O'-dibenzoy l-1-tartrate} and )-[Ru(phen)(3)]{(+)-O,O'-di-4-toluoyl-d-tartrate}. R esolution is also reported for the analogous species containing three potential bridging ligands, [Ru(bpm)(3)](2+) and [Ru(HAT)(3)](2+) (bpm = 2,2'-bipyrimidine; HAT = 1,4,5,8,9,12-hexaazatriphenylene). The ver satility of the chromatographic procedure was demonstrated by the reso lution of a series of bis-heteroleptic complexes [Ru(pp)(2)(pp')](2+) {pp' = dpq (dipyrido[3,2-d:2,3'-f]quinoxaline), dpqc ipyrido[3,2-a:2,3 -d]-6,7,8,9-tetrahydrophenazine), and dppz {dipyrido[3,2-a:2,3'-d]phen azine)}.