Acta Phys. -Chim. Sin. ›› 2006, Vol. 22 ›› Issue (05): 608-615.doi: 10.1016/S1872-1508(06)60021-1

• ARTICLE • Previous Articles     Next Articles

Absolute Asymmetry Synthesis and Resolution Mechanism of Chiral cis-bromoamminebis(ethylenediamine) cobalt(III) Bromide

ZHANG Hui;WANG Xian-Ying;CHEN Lei-Qi;FANG Xue-Ming;GAO Jing-Xing XU Zhi-Gu(608)   

  1. State Key Laboratory for Physical Chemistry of Solid Surface, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
  • Received:2005-11-09 Revised:2005-12-30 Published:2006-04-28
  • Contact: ZHANG, Hui E-mail:huizhang@jingxian.xmu.edu.cn

Abstract: The absolute asymmetric synthesis of the title complexes Λ-(+)D-cis-[CoBr(NH3)(en)2]Br2(1) and Δ-(-)D-cis-[CoBr(NH3)(en)2]Br2(2)(en=1,2-ethylenediamine) as well as the improved optical resolution of cis-[CoBr(NH3)(en)2]Br2·2H2O(3) are described in detail. The products were characterized by means of elemental analysis, TG-DTA, optical rotation, UV-Vis, and CD spectra. The distribution of enantiomeric excess(ee) of cis-[CoBr(NH3)(en)2]Br2 in the absolute asymmetric synthesis was obtained by the measurements of their CD spectra. It was found that the complete resolution of rac-cis-[CoBr(NH3)(en)2]Br2·2H2Owas achieved by use of NH4(d-BCS) (ammonium d-α-bromocamphor-π-sulfonate) or NH4(l-BCS) while NH4(dl-BCS) could only be partially resolved by chiral cis-[CoBr(NH3)(en)2]Br2 at the same condition. It is deduced that there are notable differences in the chiral discrimination of the reciprocal resolution between cis-[CoBr(NH3)(en)2]Br2 and NH4BCS.Moreover, a new“catalysis-crystal induction”mechanismin the preparation of the chiral Co(III) complex is put forward.

Key words: Absolute asymmetric synthesis;Chiral symmetry breaking;Chiral cobalt(III) complex, Optical resolution;CD spectra;Chiral discrimination