Ruthenacycles with stereogenic metal centers: Synthesis and characterization of cycloruthenated (R)(C)-(+)-N,N-dimethyl-alpha-(2-naphthyl) ethylamine(TMNA); crystal structures of [( eta(6)-C6H5Me)Ru(TMNA)(X)], (X = Cl, Br, I)

The transmetallation reaction of enantiomerically pure (R-C)-{HgCl[C10H6CH( Me)NMe2]} with the [(eta(6)-arene)RuCl2](2) dimer, where eta(6)-arene=C6H5- Me (toluene), in CH3CN at ambient temperature forms a mixture of two diaste reomeric ruthenacycles [(S-Ru, R-C) - a, major, and (R-Ru, R-C) - a', minor ] of the type {(eta(6)-arene)Ru[C10H6CH(Me)NMe2](Cl)} (1a,a') in good chemi cal and optical yields. The diastereoselectivity of chloride substitution i n 1a,a' by bromide and iodide has been determined by H-1 and C-13{H-1} NMR spectroscopy and single-crystal X-ray crystallography. The diastereoselecti vity of this type of transmetallation reaction varies as a function of both the electronic nature of the (eta(6)-arene) ligand attached to the rutheni um center and the steric nature of the chiral arylamine (de is the diastere omeric excess): [(eta(6)-benzene)Ru(TMNA)Cl] (TMNA=[C10H6CH(Me)NMe2]), 8a,a ', (92% de)>[(eta(6)-benzene)Ru(TMBA)Cl], (TMBA=[C6H4CH(Me)NMe2]), 5a,a', ( 90.4% de)>[(eta(6)-toluene)Ru(TMNA)Cl], 1a,a', (87.5% de)>[(eta(6)-toluene) Ru(TMBA)Cl], 4a,a', (86.7% de). The diastereoselectivity of the substitutio n reactions generally increases with increasing steric bulk of the incoming ligand and proceeds with predominant retention of configuration at rutheni um. (C) 1999 Elsevier Science Ltd. All rights reserved.