Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (02): 257-264.doi: 10.3866/PKU.WHXB201112091


Mirror Symmetry Breaking of cis-[Ni(NCS)2tren]: Special Chiral Conformations of Chelate Rings

LIU Cheng-Yong, YAN Jian-Xin, LIN Yi-Ji, LI Dan, FANG Xue-Ming, ZHANG Hui   

  1. State Key Laboratory of Physical Chemistry of Solid Surface, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian Province, P. R. China
  • Received:2011-09-28 Revised:2011-12-01 Published:2012-01-11
  • Contact: ZHANG Hui
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20773098, 20973136).

Abstract: In order to explore the chiral origin of cis-[Ni(NCS)2tren] [tren: tris(2-aminoethyl) amine], a pair of chiral crystals of cis-[Ni(NCS)2tren] was characterized by X-ray single crystal structural analysis, solution UV-Vis-near infrared (NIR) spectroscopy, solid state UV-circular dichiroism (CD), and powder X-ray diffraction (XRD) spectra. The results indicated that the chiral crystals of cis-[Ni(NCS)2tren] were obtained by mirror symmetry-breaking crystallization, and the special chiral ring conformations (δδλ, λλδ) of the coordinated tripod-type tren ligands are responsible for the chiral origin of cis-[Ni(NCS)2tren]. The Cotton effects of Ni(II) complexes in the solid-state UV-CD spectra are presumably attributed to the π-π* and charge-transfer chromophores of the NCS- ligands by the chiral perturbation of the helical ring conformations and metal-centered chirality. According to the statistical results of solid-state CD spectra of cis-[Ni(NCS)2tren] for twenty batch syntheses, their enantiomeric excess (ee) values are between 39% and 100%.

Key words: Chirality, Mirror symmetry breaking, Ring conformational isomerism, Tris(2-aminoethyl)amine, Solid state CD spectroscopy


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