| Abstract
| - The stepwise syntheses of novel, diastereo- or enantiopure Δ- and Λ-Ru(tris(pp)) complexes (pp = 4,4‘-disubstituted-2,2‘-bipyridine) are described, where the pp ligands may be the same, or different. The complexes contain novel ligand architectures, with chiral esters and amides at the bpy 4,4‘-positions. All reactions gave racemic products, which were resolved by chiral HPLC. NMR, UV−vis, and CD spectroscopy and X-ray crystallography afforded complete and unambiguous assignment of the absolute chirality of the studied complexes.
- The stepwise synthesis of several novel Ru(tris(pp)) complexes (pp = 4,4‘-disubstituted-2,2‘-bipyridine; substituent= H, Me, chiral ester, or chiral amide) is described, where the pp ligands may be the same, or different, in eachcomplex. All of the complexes detailed have been resolved into their pure Δ- and Λ-enantiomers or diastereomers.The complexes, which are prepared starting from RuCl3, contain novel ligand architectures, with a range of chiralesters and amides attached to the 4,4‘-positions of the bpy ligands. It was postulated that these chiral groupswould be capable of inducing chirality at the metal center, but our investigations have shown this not to be thecase, and in all reactions completely racemic products were formed. Resolution by chiral HPLC, and the subsequentcharacterization of the products through NMR, UV−vis, and circular dichroism (CD) spectroscopy, has beencarried out; the characteristics of the CD spectra have been discussed with respect to the electron-donating/withdrawing ability of the groups at the 4,4‘-positions. The X-ray crystal structure of the optically pure complexΛ-[Ru(dmbpy)2(4,4‘-bis((R)-(+)-α-phenylethylamido)-2,2‘-bipyridine)]·2PF6·2CHCl3 was obtained and solved usingdirect methods. This result, in conjunction with the CD spectra, enabled the complete and unambiguous assignmentof the stereocenters of all of the novel Ru(tris(bpy)) complexes prepared in this investigation.
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