| (TCNQ)22-基氢键分子磁体表现出非常强的反铁磁偶合作用(英文) |
| Very Strong Antiferromagnetic Coupling Interaction in (TCNQ)22- Spin Dimers H-bonding Molecular Magnetic Compound |
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| 摘要: 合成并表征了一种新的离子对化合物[4-NH2-Py][TCNQ](其中4-NH2-Py+是4-氨基吡啶阳离子，TCNQ-为7，7，8，8-四氰基对苯二醌二甲烷自由基阴离子)。在该离子对化合物晶体中，2个TCNQ-离子形成了面对面堆积的二聚体；阴离子中的氰基分别和阳离子上的氨基、吡啶质子化氮原子之间存在非常强的分子间氢键。通过氢键作用，相邻的TCNQ-二聚体被阳离子连成三维氢键网络。变温磁化率测量表明，在2~400 K温度范围内，该离子对化合物表现为抗磁性。在密度泛函理论框架下，用对称性破损方法计算了化合物晶体中π二聚体内以及通过氢键连接的相邻的TCNQ-离子之间的磁交换常数，发现π二聚体内存在非常强的反铁磁交换作用，与之相比，通过氢键连接的TCNQ-离子之间的磁交换作用可以忽略。π二聚体内强反铁磁交换作用(J/kB≈1 805 K)导致了该化合物基本表现为抗磁性。 |
| 关键词: 离子对 晶体结构 磁性 DFT计算 对称性破损 |
| 基金项目: |
| Abstract: An ion-pair type of hydrogen bonding molecular magnetic compound was prepared by means of combining the paramagnetic TCNQ-(TCNQ=7,7,8,8-tetracyanoquinodimethane) and nonmagnetic 4-aminopyridinium. The single crystal structure of the title compound shows two TCNQ- anions form an isolated -type (TCNQ)22- dimer, and the adjacent (TCNQ)22- dimers are connected by 4-aminopyridinium via strong hydrogen-bonding. The variable temperature magnetic susceptibility measurement in the temperature range of 2~400 K indicates diamagnetism characteristics of the compound. The magnetic coupling constants between the neighboring TCNQ- anions were evaluated by the broken-symmetry approach in the density functional theory (DFT) framework. The results reveal that the strong antiferromagnetic coupling interaction (J/kB≈1 805 K) within the π-type (TCNQ)22- dimer gives rise to the diamagnetism behavior for this ion-pair compound. CCDC: 779452. |
| Keywords: ion pairs crystal structure magnetic property DFT calculation broken-symmetry |
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| 摘要点击次数: 1962 |
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| 袁国军,赵顺平,任小明,孟庆金,房晨婕.(TCNQ)22-基氢键分子磁体表现出非常强的反铁磁偶合作用(英文)[J].无机化学学报,2011,27(1):167-173. |
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