Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (7): 1323-1330.doi: 10.3866/PKU.WHXB201505143

• THEORETICAL AND COMPUTATIONAL CHEMISTRY • Previous Articles     Next Articles

Coordination Structures of Metal String Complexes (n, m)[Cr3(PhPyF)4Cl2](n=2, 3, 4; m=2, 1, 0) and Relationship with External Electric Field

DING Dan-Dan1, XU Xuan1,2,3,4,5, WU Zi-Wen1, ZHOU Wo-Hua1, CHEN Rong1, XU Zhi-Guang1,2,5   

  1. 1 School of Chemistry & Environment, South China Normal University, Guangzhou 510006, P. R. China;
    2 Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, Guangzhou 510006, P. R. China;
    3 Key Laboratory of Electrochemical Technology on Energy Storage and Power Generation in Guangdong Universities, Guangzhou 510006, P. R. China;
    4 Engineering Research Center of Materials and Technology for Electrochemical Energy Storage, Ministry of Education of China, Guangzhou 510006, P. R. China;
    5 Key Laboratory of Materials for Energy Conversion and Storage of Guangzhou, Guangzhou 510006, P. R. China
  • Received:2015-03-19 Revised:2015-05-14 Published:2015-07-08
  • Contact: XU Xuan E-mail:xuxuan@scnu.edu.cn
  • Supported by:

    The project was supported by the Natural Science Foundation of Guangdong Province, China (S2012010008763), Ministry of Education Research Project of Guangdong Province, China (2010B090400184), Science and Technology Program of Guangzhou City, China (2011J4300063).

Abstract:

The coordination structures of metal string complexes (n, m)[Cr3(PhPyF)4Cl2] (HPhPyF=N, N'- phenylpyridylformamidine; n=2, 3, 4; m=2, 1, 0) with potential applications as molecular wires have been investigated using the density functional theory BP86 method by considering the effects of an external electric field (EF). Herein, n and m represent the number of benzene rings on the left and right in the PhPyF- ligand, respectively. The results show that: (1) under zero field, the three kinds of coordination modes ((2, 2), (3, 1), (4, 0)) of the four PhPyF- ligands are close in energy, which indicates that they are competitive conformations. The (2, 2) coordination mode is the most stable one. The Cl axial ligands on the two sides of (4, 0) can coordinate to Cr atoms, indicating that these two axial ligands can combine with electrodes. Moreover, the Cl4― Cr1 bond is stronger than Cl5―Cr3, different from (4, 0) [CuCuM(npa)4Cl] [PF6] (M=Pd, Pt; 2- naphthyridylphenylamine) in which the axial ligand Cl close to benzene cannot coordinate to metal atom M. (2) There is a 3-center-3-electron delocalization σ bond in the Cr36 + chain for (2, 2), (3, 1), and (4, 0), but the delocalization gradually weakens. The polarity from Cl4 to Cl5 is stronger as the coordination mode of four PhPyF- ligands becomes more consistent. (3) The geometry and electronic structure of the investigated complexes change regularly under the electric field. Because the electron transfer direction of (3, 1) and (4, 0) is the same as its molecular polarity, the bond length, spin density, charge and energy gap are more sensitive to -Z electric field. Therefore, the -Z elelctric field is beneficial to the conductivity of the molecules. Moreover, the sensitivity of the structures to electric field increases with polarity.

Key words: Metal string complex, Density functional theory, Coordination mode, Electric field, Molecular polarity

MSC2000: 

  • O641