呈现强链内铁磁耦合的EO-叠氮与羧基双重桥连一维铜链化合物:合成、晶体结构、磁性及DFT计算

摘要

An azido-Cu(Ⅱ) compound with substituted benzoate derivative, [Cu(4-Fb)(N3)(H2O)]n (1) (4-Fb=4-form-ylbenzoate), has been successfully synthesized, and then structurally and magnetically characterized.Single crystal structure analysis demonstrates that the asymmetric unit of compound 1 possesses one crystallographically independent Cu(Ⅱ) ion that exhibits distorted tetragonal pyramid geometry.Adjacent Cu(Ⅱ) ions are linked by alternating mixed-bridges of μ-1,1 (end-on, EO) azido and syn,syn-carboxylate, forming a linear 1D Cu(Ⅱ) chainlike motif.Magnetic measurements reveal that the dominant ferromagnetic coupling between adjacent Cu(Ⅱ) ions within each chain due to the counter-complementarity of the dual superexchange pathway is observed in the resulting compounds.However, the interesting plots of magnetic ordering and slow magnetic relaxation are absent in the compound.The critical structural parameter, Cu-N-Cu angle of 113.34°, is corresponding to that of known ferromangetic copper systems containing mixed carboxylate/EO-azido connectors.Magneto-structural correlations are also investigated.Moreover, density functional theory (DFT) calculations (using different methods and basis sets) have been performed on tide compound to offer qualitatively theoretical explanation for the ferromagnetic coupling between two Cu(Ⅱ) centers.%合成了一例以取代苯甲酸衍生物为辅助配体的叠氮铜化合物[Cu(4-Fb)(N3)(H2O)]n(1)(4-Fb=4-formylbenzoate),并对其结构和磁性进行了表征.单晶结构研究表明,化合物1中的最小不对称单元包含一个晶体学独立的Cu(Ⅱ)离子,中心离子呈现了扭曲的四棱锥几何构型.相邻的Cu(Ⅱ)离子之间通过交替的μ-1,1-(EO)-叠氮和syn,syn-羧酸双重桥连接成一维线性金属链.磁性研究揭示,双重桥的超交换反补偿效应导致目标化合物中链内相邻的Cu(Ⅱ)离子之间表现出强的铁磁耦合作用(J=72.1 cm-1).但是并没有观察到铁磁有序和慢磁弛豫现象.作为影响磁性能的重要结构参数,化合物中Cu-N-Cu的角度(113.34°)与已报道的含双重桥的叠氮铜体系相符.对化合物的磁构关系进行了讨论和探究.此外,密度泛函理论(DFT)计算结果为化合物中相邻Cu(Ⅱ)离子间的铁磁耦合作用提供了定性的理论解释.