Bhanja Avik, Moreno-Pineda Eufemio, Herchel Radovan, Wernsdorfer Wolfgang, Ray Debashis
Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India.
Dalton Trans. 2020 Jun 21;49(23):7968-7976. doi: 10.1039/d0dt01675f. Epub 2020 Jun 5.
The variable coordination behavior of 2-{[(2-hydroxy-3-methoxybenzyl)imino]methyl}-6-methoxyphenol (HL) and its hydrolyzed congener towards NiCl·6HO and Ln nitrate salts provides a family of coordination aggregates containing an [NiLn] octanuclear core structure. Room temperature reactions in MeOH-CHCl medium and in the presence of NEt yielded isostructural [NiLn(L)(μ-OH)(μ-OH)(o-val)(HO)]NO·7HO (Ln = Dy (1), Tb (2), and Ho (3); o-val = o-vanillin) heterometallic complexes. All the three complexes hold an octanuclear fused partial hexacubane topology from the utilization of phenolate-based ligand anions, clipping five 3d and three 4f ions. Direct current magnetic susceptibility measurements showed an upsurge at low temperature for complexes 1 and 2, indicative of ferromagnetic interactions, while antiferromagnetic exchange interaction predominates for complex 3. AC magnetic susceptibility measurements were not able to show any slow relaxation property to the magnetization. CASSCF calculations for complex 1 indicate that all three Dy centres have anisotropic axes but the relative orientation of the magnetic axes reduces the probability of this molecule to behave like an SMM which is further established by the POLY_ANISO calculations.
2-{[(2-羟基-3-甲氧基苄基)亚氨基]甲基}-6-甲氧基苯酚(HL)及其水解同系物对NiCl·6HO和镧系硝酸盐的可变配位行为提供了一族含有[NiLn]八核核心结构的配位聚集体。在MeOH-CHCl介质中、在NEt存在下于室温反应生成了同构的[NiLn(L)(μ-OH)(μ-OH)(邻香草醛)(HO)]NO·7HO (Ln = Dy (1)、Tb (2)和Ho (3)；邻香草醛 = 邻香草醛)异金属配合物。利用酚盐基配体阴离子，这三种配合物均具有八核稠合的部分六立方烷拓扑结构，连接五个3d离子和三个4f离子。直流磁化率测量表明，配合物1和2在低温下出现激增，表明存在铁磁相互作用，而配合物3中反铁磁交换相互作用占主导。交流磁化率测量未能显示出磁化的任何慢弛豫特性。对配合物1的CASSCF计算表明，所有三个Dy中心都具有各向异性轴，但磁轴的相对取向降低了该分子表现得像单分子磁体的概率，这一点通过POLY_ANISO计算进一步得到证实。
