Hexadentate chromium(III) complexes containing unsymmetrical edta-type ligands -: Part IV.: Crystal structures of (-)589-trans(O5)-Na[Cr(ed3ap)]•3H2O and Na[Cr(u-eddadp)]•3H2O and CD spectra correlation:: structural parameters of [Cr(edta-type)]- complexes and their octahedral distortion in relation to the structure of the ligand

Structural data are given for two recently reported hexadentate chromium(III) complexes: trans(O-5)-Na[Cr(ed3ap)]. 3H(2)O (A) and Na[Cr(u-eddadp)]. 3H(2)O (B) (ed3ap = ethylenediamine-N,N,N'-triacetate-N'-3-propionate ion; u-eddadp = ethylenediamine-N-diacetate-N'-di-3-propionate ion). Only one, the favored (trans(O-5)) isomer of the complex A was resolved. Also, the complex A was found to be spontaneously resolved. The absolute configuration around the chromium(III) ion in the crystal A has been determined to be Lambda(Lambda Delta Lambda). The complexes crystallize in the space group P2(1)2(1)2(1) (for A) and Pna2(1) (for B) of the orthorhombic crystal system. Final R values are 0.045 for A and 0.078 for B. The conformations of the chelate rings are found to be the envelope for the glycinate rings (R relatively flat and G with a significant deviation) and distorted skew-beat (half-chair) for the beta-alaninate rings. Structural parameters and strain analysis data of complexes A and B and related [Cr(edta-type)](-) chelates are compared and discussed in relation to the structure of the ligand and octahedral distortion of complexes. The CD spectra of the Lambda-(-)(589)-trans(O-5)-[Cr(ed3ap)](-) (A) and the other edta-type Cr(III) complexes have been correlated and discussed. (C) 1999 Elsevier Science S.A. All rights reserved.