麦思卉, 莫小婵, 吴伟青, 蔡雪萍, 彭琦, 许旋. 线性金属配合物Cr3(dpa)4Cl2及其氧化态的Cr—Cr键的理论研究[J]. 华南师范大学学报(自然科学版), 2012, 44(3). doi: 10.6054/j.jscnun.2012.06.017
引用本文: 麦思卉, 莫小婵, 吴伟青, 蔡雪萍, 彭琦, 许旋. 线性金属配合物Cr3(dpa)4Cl2及其氧化态的Cr—Cr键的理论研究[J]. 华南师范大学学报(自然科学版), 2012, 44(3). doi: 10.6054/j.jscnun.2012.06.017
Theoretical Studies on the Cr—Cr Bond in Cr3(dpa)4Cl2 and [Cr3(dpa)4Cl2]+ Linear Trichromium Complexes[J]. Journal of South China Normal University (Natural Science Edition), 2012, 44(3). doi: 10.6054/j.jscnun.2012.06.017
Citation: Theoretical Studies on the Cr—Cr Bond in Cr3(dpa)4Cl2 and [Cr3(dpa)4Cl2]+ Linear Trichromium Complexes[J]. Journal of South China Normal University (Natural Science Edition), 2012, 44(3). doi: 10.6054/j.jscnun.2012.06.017

线性金属配合物Cr3(dpa)4Cl2及其氧化态的Cr—Cr键的理论研究

Theoretical Studies on the Cr—Cr Bond in Cr3(dpa)4Cl2 and Cr3(dpa)4Cl2+ Linear Trichromium Complexes

  • 摘要: 用密度泛函理论对具有分子导线潜在应用前景的线性金属配合物Cr3(dpa)4Cl2的对称构型1,非对称构型2及其氧化态Cr3(dpa)4Cl2+3进行理论计算,并结合自然键轨道理论对配合物1~3的CrCr键进行分析.结果表明:(1)中性构型1和2中只形成Cr36+的dz2轨道组成的三中心三电子键,电子由两端向中间的Cr离域,电子由中间向两端的Cr离域,电子的离域更显著.由于离域和dpa-配体的螺旋盘绕作用,Cr36+的轨道中dxz和dyz轨道成份较小且绕金属轴(Z轴)发生不同程度的旋转,难以重叠形成键.(2)氧化态3中,因配体的螺旋作用,Cr的dxy轨道绕Z轴发生不同程度旋转而无法有效重叠形成键,故CrCr短键只存在1个键和2个键的三重键.(3)中性分子的HOMO轨道为非键轨道,电子云集中在两端Cr上,两端的Cr(2的长键端的Cr)是失电子形成氧化态3的中心.

     

    Abstract: To study the CrCr bonding in linear trichromium complexes Cr3(dpa)4Cl2, the structures of symmetrical conformation 1, unsymmetrical conformation 2 and their oxidized species Cr3(dpa)4Cl2+ 3 were investigated by density functional theory (DFT) and natural bond orbital analyses, and the following conclusions can be drawn. (1) In 1 and 2, there is only a 3-center-3-electron bond which is delocalized over the Cr36+ chain. The electron charge of dz2 orbitals transfers from terminal Cr atoms to central Cr atom with spin, while from central Cr atom to terminal Cr atoms with spin. The delocalization of electron is more remarkable. Ligated by a spiral set of dpa- ligands, the dxz and dyz orbitals of each Cr atom in two molecular orbitals turn around on metal chain (Z axis) in varying degrees and make it difficult to form bonds. (2) In 3, the spiral force from dpa- ligand also turns the dxy orbital of each Cr atom around on Z axis in varying degrees and makes it impossible to form bond in CrCr short bond. Therefore, there is only a triple bond in the short CrCr bond, which is different from a quartet CrCr bond reported by some literatures about theoretical analysis. (3) In 1 and 2, the HOMO is a nonbonding orbital concentrated mainly on terminal Cr atoms. The terminal Cr atoms act as the electron donor upon oxidization to 3.

     

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