Synthesis, characterization, and diastereoselectivity of chloride substitution reactions of cycloruthenated (R)c-(+)-N,N-dimethyl-α-(2-naphthyl) ethylamine

The transmetalation reaction of enantiomerically pure (R)(C)-{HgCl[C10H6CH(Me)NMe2]}, 1, with [(eta(6)-C6H6)RuCl2](2) in CH3CN at ambient temperature forms a mixture of two diastereomeric ruthenacycles (S-Ru, R-C), 2a, (96%) and (R-Ru, R-C), 2a', (4%) of the type {(eta(6)-C6H6)Ru[C10H6CH(Me)NMe2](Cl)} in good chemical and optical yields. The diastereoselectivity of chloride substitution in 2a,a' by bromide, iodide, azide, cyanate, thiocyanate, nitrite, allylisonitrile, and selected nitrogen and phosphorus donor ligands has been determined by an appropriate combination of H-1, C-13{H-1}, and P-31{H-1} NMR spectroscopy, UV-visible spectroscopy, circular dichroism, and single-crystal X-ray crystallography. The diastereoselectivity generally increases with increasing steric bulk of the incoming ligand and proceeds with predominant retention of configuration at ruthenium. The ambidentate ligands, cyanate, thiocyanate, and nitrite all bond to ruthenium exclusively through their nitrogen donor atoms.