基于席夫碱分隔配体的Cu⁃Tb单分子磁体的阴离子调控

Anionic Modification of the Cu⁃Tb Single⁃Molecule Magnets Based on the Compartmental Schiff⁃Base Ligand

基于席夫碱分隔配体H_(2)vanophen(1,2-苯二胺缩邻香草醛),通过引入不同的阴离子,构筑了3个Cu-Tb基金属配合物[Cu_(2)(vanophen)_(2)TbCl_(2)(MeOH)_(2)]Cl·3MeOH(1)、[Cu_(2)(vanophen)_(2)TbCl_(2)(MeOH)_(2)](TCNQ)1.5·2MeOH(2)和[Cu_(2)(vanophen)_(2)Tb_(2)(N3)_(6)]·2MeOH(3)(TCNQ=7,7,8,8-四氰基对苯二醌二甲烷),并详细研究了它们的结构和磁性。除了抗衡阴离子外,配合物1和2具有非常相似的[CuTbCu]三核结构;其中Cu(Ⅱ)离子处于席夫碱配体中的[N_(2)O_(2)]配位口袋中,而Tb(Ⅲ)离子则和配体中的[O_(4)]配位口袋中的全部或部分O原子配位。对应于一个三核基元,配合物1中的抗衡阴离子为一个Cl^(-)离子,而配合物2中的抗衡阴离子是一个TCNQ^(-0.5)阴离子及半个TCNQ-阴离子。配合物3是由end-end及end-on叠氮桥联2个[CuTb]单元形成的四核[CuTb]_(2)配合物。磁性研究表明,三核配合物1和2均为场致的单分子磁体而配合物3为零场单分子磁体,其中配合物1和3的能垒分别为(11.1±0.3)cm^(-1)和(20.2±0.3)cm^(-1)。相比于配合物1,配合物2具有更低的能垒,这可能源于其中的阴离子自由基和三核[CuTbCu]基元之间的弱的磁相互作用。

By using different anions,three Cu-Tb metal complexes,namely[Cu_(2)(vanophen)_(2)TbCl_(2)(MeOH)_(2)]Cl·3MeOH(1),[Cu_(2)(vanophen)_(2)TbCl_(2)(MeOH)_(2)](TCNQ)1.5·2MeOH(2),and[Cu_(2)(vanophen)_(2)Tb_(2)(N3)_(6)]·2MeOH(3),based on the compartmental Schiff-base ligand H_(2)vanophen(H_(2)vanophen=N,N′-bis(2-oxy-3-methoxybenzylidene)-1,2-phenylenediamine,TCNQ=7,7,8,8-tetracyanoquinodimethane)have been synthesized and characterized structurally and magnetically.Except for the different charge-balancing anions,complexes 1 and 2 have a very similar trinuclear[CuTbCu]structure,where the Cu(Ⅱ)ions are in the[N_(2)O_(4)]coordination pockets of the ligands,while the Tb(Ⅲ)ion is coordinated by all or some of the oxygen atoms from the[O_(4)]pocket of the ligands.The charge-balancing anion is a Cl^(-)ion in 1,while the positive charge is balanced by one TCNQ^(-0.5)radical and a half of the TCNQ-radical in 2.As for complex 3,it has a tetranuclear[CuTb]_(2)structure,where two[CuTb]units are bridged by end-end and end-on azides.Magnetic studies revealed that both 1 and 2 are field-induced SMMs while 3 is a zero-field SMM.The energy barriers of 1 and 3 were estimated to be(11.1±0.3)cm^(-1)and(20.2±0.3)cm^(-1),respectively.As for complex 2,its energy barrier was lower than that of 1,which might be due to the weak magnetic interaction between the[CuTbCu]unit and the paramagnetic radical anions.CCDC:2165235,1;2165236,2;2165237,3.