Magneto-Structural Characterization of Heterometallic NiII2MnII2/NiII2CoII2 Cubane Complexes with a Compartmental Ligand

IF 4.3 2区化学 Q1 CHEMISTRY, INORGANIC & NUCLEAR

Inorganic Chemistry Pub Date : 2025-04-17 DOI:10.1021/acs.inorgchem.4c05065

Anangamohan Panja, Erik Čižmár, Narayan Ch. Jana, Paula Brandão, Rakhi Nandy

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Abstract

We report a combined experimental and theoretical magneto-structural study of four heterometallic isostructural complexes: [Ni₂Mn₂(L)₂(OAc)₂{N(CN)₂}]·5H₂O (1), [Ni₂Mn₂(L)₂(OAc)₂(N₃)₂]·MeCN (2), [Ni₂Mn₂(L)₂(OAc)₂(NCS)₂]·H₂O (3), and [Ni₂Co₂(L)₂(OAc)₂(NCS)₂]·4H₂O (4). These complexes were synthesized using a compartmental Schiff base ligand, N,N′-bis(3-methoxy-5-methylsalicylidene)-2,2-dimethyl-1,3-diaminopropane (H₂L), and various pseudohalide ions. X-ray crystallography reveals cubane-like structures featuring a {Ni₂M₂(μ₃-O)₄} (M = Mn or Co) core. The Ni^II centers invariably exhibit octahedral geometry, while Mn^II and Co^II ions adopt hepta-coordinated pentagonal bipyramidal geometries. Magnetic studies, ab initio calculations, and BS-DFT analyses reveal competing ferromagnetic (FM) and antiferromagnetic (AFM) exchange interactions. The heterometallic exchange via an additional μ-O,O′-acetate ligand is FM, contrasting with mostly AFM interactions through the two μ₃-O bridges. Ni^II ions in 1–4 display moderate easy-plane single-ion anisotropy, while complex 4 uniquely features hepta-coordinated Co^II ions with easy-axis anisotropy of D_Co ≈ −23 cm^–1. Moreover, a field-induced slow magnetic relaxation was observed in 4, governed by a direct relaxation process. Notably, this is the first report of a Ni₂Mn₂ cubane structure, with only one prior example of a Ni₂Co₂ cubane complex in the literature. Thus, this study uncovers the magneto-structural properties of rare Ni₂Mn₂ and Ni₂Co₂ systems while highlighting 4 as a unique case of hepta-coordinated Co^II ions with significant easy-axis anisotropy and slow magnetization relaxation, enriching the molecular magnetism landscape.

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含区隔配体的NiII2MnII2/NiII2CoII2立方烷异质金属配合物的磁结构表征

本文报道了四种异金属异质结构配合物：[Ni2Mn2(L)2(OAc)2{N(CN)2}]·5H2O(1)、[Ni2Mn2(L)2(OAc)2(N3)2]·MeCN(2)、[Ni2Mn2(L)2(OAc)2（NCS)2]·H2O(3)）和[Ni2Co2(L)2(OAc)2 [NCS)2]·4H2O(4)。这些配合物是用室状希夫碱配体N，N ' -双（3-甲氧基-5-甲基水杨基）-2,2-二甲基-1,3-二氨基丙烷（H2L）和各种假卤化物离子合成的。x射线晶体学显示具有{Ni2M2(μ3-O)4} （M = Mn或Co）核心的立方体结构。NiII中心总是呈现八面体几何形状，而MnII和CoII离子则采用七协调的五边形双锥体几何形状。磁学研究、从头计算和BS-DFT分析揭示了相互竞争的铁磁（FM）和反铁磁（AFM）交换相互作用。通过附加的μ-O，O ' -乙酸配体进行的异金属交换是FM，而不是通过两个μ-O桥进行的AFM相互作用。1-4中的NiII离子表现出中等的易平面单离子各向异性，而配合物4特有的七配位CoII离子具有DCo≈−23 cm-1的易轴各向异性。此外，在4中还观察到场致慢磁弛豫，这是由直接弛豫过程控制的。值得注意的是，这是Ni2Mn2立方体结构的第一篇报道，文献中只有一个Ni2Co2立方体配合物的例子。因此，本研究揭示了稀有Ni2Mn2和Ni2Co2体系的磁结构性质，同时突出了4作为七配位CoII离子的独特案例，具有显著的易轴各向异性和缓慢的磁化弛豫，丰富了分子磁性景观。

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来源期刊

Inorganic Chemistry 化学-无机化学与核化学

CiteScore

7.60

自引率

13.00%

发文量

1960

审稿时长

1.9 months

期刊介绍： Inorganic Chemistry publishes fundamental studies in all phases of inorganic chemistry. Coverage includes experimental and theoretical reports on quantitative studies of structure and thermodynamics, kinetics, mechanisms of inorganic reactions, bioinorganic chemistry, and relevant aspects of organometallic chemistry, solid-state phenomena, and chemical bonding theory. Emphasis is placed on the synthesis, structure, thermodynamics, reactivity, spectroscopy, and bonding properties of significant new and known compounds.