电场作用下金属串配合物[Cr_3(dpza)_4L_2](L=Cl,NCS)的结构

The structure of metal string complexes Cr_3(dpza)_4L_2(dpza=dipyrazylamine,L=Cl,NCS) under the electric field

用UBP86方法研究了金属串配合物[Cr_3(dpza)_4Cl_2](1)和[Cr_3(dpza)_4(NCS)_2](2)在外电场作用下的几何和电子结构的变化规律。发现随电场增大,高电势端的Cr-Cl和Cr-N键增长,而低电势端的Cr-Cl和Cr-N键缩短。轴向配体L的负电荷由低电势端向高电势端转移,1中原子的自旋密度变化很小,2中低电势端的Cr原子和L的自旋密度变化较明显。随电场增大,分子能量下降,偶极矩呈线性增大:HOMO和HOMO-1轨道能升高且轨道分布移向低电势端,相反,LUMO轨道能减小且轨道分布移向高电势端,使HOMO-LUMO能隙减小,有利于金属链的导电性。电场对2的上述结构和性质的影响尤为显著。

The geometrical and electronic structures of string complexes [Cr_3（dpza）4Cl_2]（lS） and [Cr3（dpza）4（NCS）2]（2U） were investigated theoxeticaUy with density functional theory UBP86 method by incorporating the external electric field. The electric field results the elongation of Cr-Cl or Cr-N distances at the high potential end while the contraction at the low potential end. The negative charge of L （L=CI, NCS） moves to the high potential side. The spin density of 1S changes a little, while that of 2U at the low potential side is sensitive to the electric field. With the increase of the electric field, the molecular energy decreases and the dipole moment increases linearly. Moreover, the spatial distributions of HOMO（onb） and HOMO-1 （πnb） move to the low potential end with the orbital energies increasing, while that of LUMO changes oppositely. This results in the decreasing of HOMO-LUMO gap which is beneficial to electron-transport properties of the metal string complexes. Above geometric and electric structures of 2U are much more sensitive to the electric field than 1S.