Vassilyeva Olga Yu, Buvaylo Elena A, Kokozay Vladimir N, Skelton Brian W, Sobolev Alexandre N, Bieńko Alina, Ozarowski Andrew
Department of Chemistry, Taras Shevchenko National University of Kyiv, 64/13 Volodymyrska str., Kyiv 01601, Ukraine.
School of Molecular Sciences, M310, University of Western Australia, Perth, WA 6009, Australia.
Dalton Trans. 2021 Mar 2;50(8):2841-2853. doi: 10.1039/d0dt03957h.
Three new NiII/ZnII heterometallics, [NiZnL'2(OMe)Cl]2 (1), [NiZnL''(Dea)Cl]2·2DMF (2) and [Ni2(H3L''')2(o-Van)(MeOH)2]Cl·[ZnCl2(H4L''')(MeOH)]·2MeOH (3), containing three-dentate Schiff bases as well as methanol or diethanolamine (H2Dea) or o-vanillin (o-VanH), all deprotonated, as bridging ligands were synthesized and structurally characterized. The Schiff base ligands were produced in situ from o-VanH and CH3NH2 (HL'), or NH2OH (HL"), or 2-amino-2-hydroxymethyl-propane-1,3-diol (H4L'''); a zerovalent metal (Ni and Zn in 1, Zn only in 2 and 3) was employed as a source of metal ions. The first two complexes are dimers with a Ni2Zn2O6 central core, while the third compound is a novel heterometallic cocrystal salt solvate built of a neutral zwitterionic ZnII Schiff base complex and of ionic salt containing dinuclear NiII complex cations. The crystal structures contain either centrosymmetric (1 and 2) or non-symmetric di-nickel fragment (3) with NiNi distances in the range 3.146-3.33 Å. The exchange coupling is antiferromagnetic for 1, J = 7.7 cm-1, and ferromagnetic for 2, J = -6.5 cm-1 (using the exchange Hamiltonian in a form Ĥ = Jŝ1ŝ2). The exchange interactions in 1 and 2 are comparable to the zero-field splitting (ZFS). High-field EPR revealed moderate magnetic anisotropy of opposite signs: D = 2.27 cm-1, E = 0.243 cm-1 (1) and D = -4.491 cm-1, E = -0.684 cm-1 (2). Compound 3 stands alone with very weak ferromagnetism (J = -0.6 cm-1) and much stronger magnetic anisotropy with D = -11.398 cm-1 and E = -1.151 cm-1. Attempts to calculate theoretically the exchange coupling (using the DFT "broken symmetry" method) and ZFS parameters (with the ab initio CASSCF method) were successful in predicting the trends of J and D among the three complexes, while the quantitative results were less good for 1 and 3.
合成并表征了三种新型镍（II）/锌（II）异金属配合物，即二氯·二甲氧基·双[二齿席夫碱锌（II）镍（II）]（1）、二氯·二乙醇胺·双[二齿席夫碱锌（II）镍（II）]·2二甲基甲酰胺（2）和氯·甲醇·双[二齿席夫碱镍（II）]·[二氯·甲醇·四齿席夫碱锌（II）]·2甲醇（3），它们均含有去质子化的三齿席夫碱以及甲醇、二乙醇胺（H₂Dea）或邻香草醛（o-VanH）作为桥联配体。席夫碱配体由邻香草醛（o-VanH）与甲胺（HL'）、羟胺（HL''）或2-氨基-2-羟甲基丙烷-1,3-二醇（H₄L'''）原位生成；零价金属（1中的镍和锌，2和3中仅锌）用作金属离子源。前两种配合物是具有Ni₂Zn₂O₆中心核的二聚体，而第三种化合物是由中性两性离子锌（II）席夫碱配合物和含双核镍（II）配合物阳离子的离子盐构成的新型异金属共晶溶剂化物。晶体结构包含中心对称（1和2）或非对称的二镍片段（3），镍镍距离在3.146 - 3.33 Å范围内。配合物1的交换耦合是反铁磁性的，J = 7.7 cm⁻¹，配合物2是铁磁性的，J = -6.5 cm⁻¹（使用形式为Ĥ = Jŝ₁ŝ₂的交换哈密顿量）。配合物1和2中的交换相互作用与零场分裂（ZFS）相当。高场电子顺磁共振揭示了相反符号的适度磁各向异性：D = 2.27 cm⁻¹，E = 0.243 cm⁻¹（1）和D = -4.491 cm⁻¹，E = -0.684 cm⁻¹（2）。化合物3具有非常弱的铁磁性（J = -0.6 cm⁻¹）和更强的磁各向异性，D = -11.398 cm⁻¹，E = -1.151 cm⁻¹。尝试通过理论计算交换耦合（使用密度泛函理论“破缺对称性”方法）和ZFS参数（从头算CASSCF方法）成功预测了三种配合物中J和D的趋势，而对于配合物1和3的定量结果不太理想。
