CAJ | 학술논문

?? nb ?¤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,链形成了三中心四电子键().(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1≈3>2>4.(3)预测了3和4的Jab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.
?? nb ?¤응용밀도범함이론BP86방법결합자연건궤도분석방법대구유분자도선잠재응용전경적금속천배합물[Ni3(L)4(NCS)2](L = dpa–(1), mpta–(2), mdpa–(3), mppa–(4))진행연구,분석료교련배체L대Ni―Ni상호작용화자우합성질적영향.결과득도：(1)배합물적기태균시대응우오중태(HS)적반철자(AF)단중태, HS적능량화결구여AF태상근,련형성료삼중심사전자건().(2) dpa–인입갑기성위mdpa–,대Ni―Ni、Ni―N거리영향불대；3H-필각배화새서배취대필정배후, N1―N2、Ni―Ni거리증대, Ni2―N2건장축단,단새서배적영향교소；고Ni―Ni상호작용강도위1≈3>2>4.(3)예측료3화4적Jab치위–103화–88 cm–1,수Ni―Ni상호작용증강자우합효응증대. Ni―Ni상호작용월대,통과련σ형궤도적직접자우합월강；Ni2―N2건월강,통과섭급교련배체적간접자우합월강,직접자우합비간접자우합경강.
? ? ?nb ?¤ 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 folowing 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 bonds ( ) along the 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 is1 ≈3 >2 >4. (3) The predictedJab values of3 and4 ? 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 orbitals along the 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.