Highly diastereoselective preparation of ruthenium bis(diimine) sulfoxide complexes: New concept in the preparation of optically active octahedral ruthenium complexes
F. Pezet et al., Highly diastereoselective preparation of ruthenium bis(diimine) sulfoxide complexes: New concept in the preparation of optically active octahedral ruthenium complexes, ORGANOMETAL, 19(20), 2000, pp. 4008-4015
Microwave irradiation of racemic cis-[Ru(bpy)(2)(Cl)(2)] (bpy = 2,2'-bipyri
dine) or racemic cis[Ru(phen)(2)(Cl)(2)] (phen phenanthroline) with either
(R)-(+)- or (S)-(-)-methyl p-tolyl sulfoxide yielded the ruthenium bis(diim
ine) sulfoxide complexes with a high level of asymmetric induction (13-76%
de). Stereochemistry at the metal center for the major isomer was determine
d by X-ray study of [Ru(bpy)(2)(dmbpy)]. 2PF(6), obtained by reaction of co
mplex 3 with 4,4'-dimethyl-2,2'-bipyridine and confirmed by X-ray study of
the complex 7. The absolute configuration at the metal center for the minor
isomer was established by X-ray study of the minor isomer derived from the
reaction of cis-[Ru(bpy)(2)(Cl)(2)] with (S)-(-)-methyl p-tolyl sulfoxide.
Structural analysis of Delta-7 (major isomer) revealed the presence of two
intramolecular interactions, oxygen-hydrogen interaction and pi-pi stackin
g of the pyridyl-tolyl rings, while the structural analysis of Delta-5 (min
or isomer) showed only the presence of the oxygen-hydrogen interaction. The
importance of these interactions in this transformation was confirmed by t
he reaction of cis-[Ru(2,9-dimethyl-1,10-phenanthroline)(2)Cl-2]with (R)-()-methyl p-tolyl sulfoxide, which gave, in acetonitrile, the complex cis-[R
u(2,9-dimethyl-1,10-phenanthroline)(2)(CH3CN)(2)]. 2PF(6), 10. Oxygen-hydro
gen and pi-pi interactions are used to explain both the reactivity of cis-[
Ru(diimine)(2)Cl-2] with the sulfoxide and the stability of the major isome
r when enantiomerically pure sulfoxide was used.