高等学校化学学报 ›› 2009, Vol. 30 ›› Issue (8): 1605.

• 研究论文 • 上一篇    下一篇

异双核X-M之间的磁耦合交换作用: Keggin型杂多酸衍生物[M(H2O)XW11O39]7-(X=Fe, Co; M=Co)的密度泛函研究

方亮, 关威, 颜力楷, 苏忠民   

  1. 东北师范大学化学学院功能材料化学研究所, 长春 130024
  • 收稿日期:2008-05-21 出版日期:2009-08-10 发布日期:2009-08-10
  • 通讯作者: 苏忠民, 男, 博士, 教授, 博士生导师, 主要从事量子化学研究. E-mail: zmsu@nenu.edu.cnKeggin
  • 基金资助:

    国家自然科学基金(批准号: 20703008)和“长江学者和创新团队”发展计划(批准号: IRT0714)资助.

Density Functional Studies of Magnetic Exchange of Biheteroatom 11-Heteropoly Complexes: [M(H2O)XW11O39]7-(X=Fe, Co; M=Co)

FANG Liang, GUAN Wei, YAN Li-Kai, SU Zhong-Min*   

  1. Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024, China
  • Received:2008-05-21 Online:2009-08-10 Published:2009-08-10
  • Contact: SU Zhong-Min. E-mail: zmsu@nenu.edu.cnKeggin
  • Supported by:

    国家自然科学基金(批准号: 20703008)和“长江学者和创新团队”发展计划(批准号: IRT0714)资助.

摘要:

采用DFT-BS方法研究异双核的Keggin型杂多酸衍生物[M(H2O)XW11O39]7-(Ⅰ: X=Fe, M=Co; Ⅱ: X=Co, M=Co)的磁耦合作用, 计算得到耦合常数(J)为负值, 表明所研究体系具有反铁磁性; J值大小顺序为|J(Ⅰ)|<|J(Ⅱ)|, 说明磁耦合作用增强; 体系Ⅰ与Ⅱ相比, X由Fe变成Co, M不变, 桥氧原子Ob和Ob2(O′b2)上的自旋密度增大, 进一步从相关BS态的磁轨道比较得出, 体系Ⅱ中轨道重叠程度大于体系Ⅰ, 结果使X-M之间的反铁磁耦合作用加强.

关键词: Keggin型杂多酸衍生物; 磁交换作用; 磁耦合交换常数; 破损态方法; 密度泛函理论

Abstract:

The magnetic exchange interactions for the biheteroatom 11-heteropoly complexes: [M(H2O)XW11O39]n-(Ⅰ: X=Fe, M=Co; Ⅱ: X=Co, M=Co) were investigated via density functional theory combined with broken-symmetry approach(DFT-BS) method. The calculated J values are -35 cm-1(Ⅰ) and -44 cm-1(Ⅱ), respectively, which show that antiferromagnetic exchange interactions exist in these complexes. The order of the absolute value of J is: |J(Ⅰ)|<|J(Ⅱ)|, indicating the increase of coupling interaction from system Ⅰ to Ⅱ. With the change of the heteroatom X via Fe(Ⅰ)→Co(Ⅱ), the spin densities on bridge oxygen atoms Ob and Ob2(O′b2) increase. Furthermore, from the comparison of BS magnetic orbitals in system Ⅰ and Ⅱ we find the overlap of relative orbitals in system Ⅱ enlarges. Consequently, a stronger antiferromagnetic coupling arises in system Ⅱ than in Ⅰ.

Key words: Keggin-type heteropolyoxometalate derivative; Magnetic exchange interaction; Magnetic coupling constant; Broken-symmetry approach; Density functional theory

TrendMD: