M. Enamullah, A. Sharmin, M. Hasegawa
Jun 1, 2006
Citations
0
Influential Citations
79
Citations
Quality indicators
Journal
European Journal of Inorganic Chemistry
Abstract
The dimeric complex acetato(η4-cycloocta-1,5-diene)rhodium(I), [Rh(O2CMe)(η4-cod)]2 (cod = cycloocta-1,5-diene), reacts with amino acids [HAA = L-alanine, (S)-2-amino-2-phenylacetic acid (L-phenylglycine), N-methylglycine, and N-phenylglycine] and with the amino alcohol (S)-2-amino-2-phenylethanol to afford the aminocarboxylato(η4-cycloocta-1,5-diene)rhodium(I) complexes [Rh(AA)(η4-cod)] (AA = deprotonated amino acid = aminocarboxylato ligand) and [(S)-2-amino-2-phenylethanol](η4-cycloocta-1,5-diene)rhodium(I) acetate, [Rh{(S)-HOCH2–CH(Ph)-NH2}(η4-cod)](O2CMe) (V). The complexes are characterized by IR, UV/Vis, 1H/13C NMR and mass spectroscopy. The achiral N-phenylglycine ligand gives a chiral N-phenylglycinato complex [Rh(O2C–CH2–NHPh)(η4-cod)] (IV) with the amine nitrogen atom becoming the stereogenic center upon metal coordination. Complex IV crystallizes in the tetragonal, chiral space group P43 and the crystal structure reveals twofold spontaneous resolution of a racemic mixture into homochiral helix-enantiomers. The investigated crystal contained only one type of helix, namely (left-handed or M-) 43-helical chains. This is traced first to an intermolecular N–H···O hydrogen bonding from the stereogenic amino group to a neighboring unligated carboxyl oxygen atom that connects only molecules of the same (R)-configuration into (left-handed or M-) 43-helical chains. This intrachain homochirality is supplemented, secondly, by the interlocking of adjacent chains with their corrugated van der Waals surface to allow for an interchain transmission of the sense of helicity, building the single crystal from the same homochiral helix-enantiomer. The enantiomeric amino alcohol complex V crystallizes in the monoclinic, noncentrosymmetric (Sohncke) space group P21. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)