物理化学学报 >> 2015, Vol. 31 >> Issue (9): 1683-1689.doi: 10.3866/PKU.WHXB201506031

理论与计算化学 上一篇    下一篇

金属串配合物[Ni3(L)4(NCS)2](L = dpa-, mpta-, mdpa-, mppa-)结构和磁性的理论研究

陈蓉1,周沃华1,吴子文1,许旋1,2,3,*(),徐志广1   

  1. 1 华南师范大学化学与环境学院,广州510006
    2 教育部环境理论化学重点实验室,广州510006
    3 广州市能源转化与储能材料重点实验室,广州510006
  • 收稿日期:2015-02-16 发布日期:2015-09-06
  • 通讯作者: 许旋 E-mail:xuxuan@scnu.edu.cn
  • 基金资助:
    广东省自然科学基金(S2012010008763);广东省教育部产学研项目(2010B090400184);广州市科技攻关项目(2011J4300063)

Theoretical Study on the Structures and Magnetic Properties of Metal String Complexes [Ni3(L)4(NCS)2] (L = dpa-, mpta-, mdpa-, mppa-)

Rong. CHEN1,Wo-Hua. ZHOU1,Zi-Wen. WU1,Xuan. XU1,2,3,*(),Zhi-Guang. XU1   

  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 Materials for Energy Conversion and Storage of Guangzhou, Guangzhou 510006, P. R. China
  • Received:2015-02-16 Published:2015-09-06
  • Contact: Xuan. XU E-mail:xuxuan@scnu.edu.cn
  • Supported by:
    the Natural Science Foundation of Guangdong Province, China(S2012010008763);Ministry of Education andGuangdong Province, China(2010B090400184);Science and Technology Program of Guangzhou City, China(2011J4300063)

摘要:

应用密度泛函理论BP86方法结合自然键轨道分析方法对具有分子导线潜在应用前景的金属串配合物[Ni3(L)4(NCS)2](L = dpa- (1), mpta- (2), mdpa- (3), mppa- (4))进行研究,分析了桥联配体L对Ni―Ni相互作用和磁耦合性质的影响.结果得到: (1)配合物的基态均是对应于五重态(HS)的反铁磁(AF)单重态, HS的能量和结构与AF态相近, Ni36+链形成了三中心四电子σ键(σ2σnb1σ*1). (2) dpa-引入甲基成为mdpa-,对Ni―Ni、Ni―N距离影响不大; 3H-吡咯环和噻唑环取代吡啶环后, N1―N2、Ni―Ni距离增大, Ni2―N2键长缩短,但噻唑环的影响较小;故Ni―Ni相互作用强度为13 > 2 > 4. (3)预测了34Jab值为-103和-88 cm-1,随Ni―Ni相互作用增强磁耦合效应增大. Ni―Ni相互作用越大,通过Ni36+链σ型轨道的直接磁耦合越强; Ni2―N2键越强,通过涉及桥联配体的间接磁耦合越强,直接磁耦合比间接磁耦合更强.

关键词: 金属串配合物, 桥联配体, 密度泛函理论, 磁耦合, 分子导线

Abstract:

Density functional theory at the BP86 level and natural bond orbital theory were used to investigate the influence of bridging ligands on the Ni―Ni interactions and magnetic coupling properties of metal string complexes [Ni3(L)4(NCS)2] (L = 1: dpa- (dipyridylamine), 2: mpta- (4-methylpyridyl-thiazolylamine), 3: mdpa- (4-methyl-dipyridylamine), 4: mppa-(4-methylpyridyl-3H-pyrrolylamine)) with potential applications in molecular wires. The following conclusions can be drawn. (1) The ground states of the complexes are antiferromagnetic (AF) singlet states, which correspond to the quintet state (HS). The energy and structure of HS is similar to AF. There are three-center-four-electron σ bonds (σ2σnb1σ*1) along the Ni36+ chains. (2) The Ni―Ni and Ni―N distances are unaffected by methyl substituents on the pyridine ring of dpa- ligands. However, substitution of the 3H-pyrrole ring or thiazole ring by the pyridine ring in mdpa- lengthens the N1―N2 and Ni―Ni distances but shortens the Ni2―N2 distance. These effects of the thiazole ring are weaker than those of the 3H-pyrrole ring. Therefore, the strength of the Ni―Ni interaction is 13 > 2 > 4. (3) The predicted Jab values of 3 and 4 are -103 and -88 cm-1, respectively. The AF magnetic coupling effects of the complexes increase with increasing Ni―Ni interaction strength: the stronger the Ni―Ni interaction, the greater the direct magnetic coupling in the σ orbitals along the Ni36+ chains. In addition, the stronger the Ni2―N2 interaction, the larger the indirect magnetic coupling involving the bridging ligand. The direct magnetic coupling is stronger than the indirect magnetic coupling.

Key words: Metal string complex, Bridging ligand, Density functional theory, Magnetic coupling, M olecular wire

MSC2000: 

  • O641