TY - JOUR
T1 - Pairing of propellers
T2 - Dimerization of octahedral ruthenium(II) and osmium(II) complexes of eilatin via π-π stacking featuring heterochiral recognition
AU - Gut, Dalia
AU - Rudi, Amira
AU - Kopilov, Jacob
AU - Goldberg, Israel
AU - Kol, Moshe
PY - 2002/5/15
Y1 - 2002/5/15
N2 - Five octahedral eilatin complexes of the type [M(L-L)2(eilatin)]2+ (M = Ru, Os; L-L = bipyridyl-type ligands) were synthesized, and their dimerization via π-π stacking was studied by crystallography and 1H NMR techniques. The X-ray structures of these racemic complexes were solved and revealed that the eilatin complexes are organized as discrete dimers in which the eilatin residues of each complex are stacked in centrosymmetric packing. Chemical shift dependence on concentration in the 1H NMR spectra support fast dimer - monomer equilibrium, and the structures of the dimers in acetonitrile solution are proposed to be analogous to their solid-state structures. Dimerization constants in acetonitrile were measured for the five racemic eilatin complexes that exhibit different structural parameters, as well as for the two enantiomeric forms of one of these complexes. They were found to be independent of the metal (Ru vs Os), strongly dependent on the steric effects introduced by the L-L ligands (2,2′-bipyridine, 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, and 2,2′-biquinoline), and dependent on the optical purity of the complexes. A clear preference for heterochiral over homochiral dimer formation was demonstrated. This is the first report of chiral recognition in solution, exhibited by simple chemical systems held solely by π-stacking interactions.
AB - Five octahedral eilatin complexes of the type [M(L-L)2(eilatin)]2+ (M = Ru, Os; L-L = bipyridyl-type ligands) were synthesized, and their dimerization via π-π stacking was studied by crystallography and 1H NMR techniques. The X-ray structures of these racemic complexes were solved and revealed that the eilatin complexes are organized as discrete dimers in which the eilatin residues of each complex are stacked in centrosymmetric packing. Chemical shift dependence on concentration in the 1H NMR spectra support fast dimer - monomer equilibrium, and the structures of the dimers in acetonitrile solution are proposed to be analogous to their solid-state structures. Dimerization constants in acetonitrile were measured for the five racemic eilatin complexes that exhibit different structural parameters, as well as for the two enantiomeric forms of one of these complexes. They were found to be independent of the metal (Ru vs Os), strongly dependent on the steric effects introduced by the L-L ligands (2,2′-bipyridine, 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, and 2,2′-biquinoline), and dependent on the optical purity of the complexes. A clear preference for heterochiral over homochiral dimer formation was demonstrated. This is the first report of chiral recognition in solution, exhibited by simple chemical systems held solely by π-stacking interactions.
UR - http://www.scopus.com/inward/record.url?scp=0037093842&partnerID=8YFLogxK
U2 - 10.1021/ja012636b
DO - 10.1021/ja012636b
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AN - SCOPUS:0037093842
SN - 0002-7863
VL - 124
SP - 5449
EP - 5456
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 19
ER -