Collect. Czech. Chem. Commun. 1997, 62, 1205-1213

Coordination Chemistry of N-(2-Hydroxybenzyl)-(S)-amino Acids. Absolute Configuration of LAMBDA-mer-R,R-[Co(ohb-(S)-Ala)2]- Anion

Svetlana Pakhomovaa, Jan Ondráčeka and František Jursíkb

a Department of Solid State Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic
b Department of Inorganic Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic


The crystal and molecular structure of the Ag[Co(ohb-(S)-Ala)2] . 5 H2O have been determined by X-ray diffraction method. The crystals are hexagonal with a = b = 9.039(0.002) Å, c = 24.896(0.006) Å, space group P3221, and Z = 3. Each Ag+ counterion coordinated by one water molecule which is a part of hydrogen bond network, is bonded to aromatic rings. The anion adopts LAMBDA-mer absolute configuration. Mer geometry is in accord with the molecular mechanics calculations. Since CD spectroscopy does not reflect configurational chirality, the absolute configuration has been determined by the X-ray structure analysis and assigned using chirality descriptors. The arrangements at the chiral centers are R for both N atoms. The two five-membered rings each assume envelope conformation with C1 and C2 atoms exceptionally deviated (0.378(7) and 1.210(7) Å) from the N-Co-O plane. Both six-membered rings have delta twist boat conformations. The complex described has been also characterized by the electronic and 13C NMR spectroscopies.

Keywords: N-Terminal tyrosine-like metal complex; N-(2-Hydroxybenzyl)-(S)-alaninato(2-) ligand; LAMBDA-mer-R,R-(lambda,lambda-delta,delta)-Ag[Co(ohb-(S)-Ala)2] absolute configuration.