Herein we report the first examples of single-molecule magnet (SMM) behaviour in S = 1/2 Ni(III) complexes. We find that low-spin 3d⁷trans-[Ni^III(cyclam)(X)₂]Y complexes (cyclam = 1,4,8,11-tetraazacyclotetradecane; X and Y are singly charged anions) exhibit field-induced slow relaxation of magnetization for O-donor axial ligands (nitrate) but not for N-donor variants (isothiocyanate). Experimental and electronic structure computational investigations indicate that intrinsic spin polarisation of low-spin Ni(III) is modulated significantly by local coordination geometry and supramolecular interactions. Solid state dilution of Ni(III) with diamagnetic Co(III) ions forms a related complex salt, [Ni_xCo_1−x(cyclam)(NO₃)₂](NO₃)·2HNO₃ (0.1 < x < 1), which preserves slow magnetic dynamics, thus supporting a molecular component to slow relaxation. An initial analysis of magnetic relaxation lifetime fits best to a combination of Raman and direct relaxation processes.

中文翻译：

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八面体低自旋 Ni(iii) 配合物中的慢磁弛豫†

在此，我们报告了S = 1/2 Ni( III ) 配合物中单分子磁体 (SMM) 行为的第一个例子。我们发现低自旋 3d ⁷ trans -[Ni ^III (cyclam)(X) ₂ ]Y 配合物（cyclam = 1,4,8,11-四氮杂环十四烷；X 和 Y 是单电荷阴离子）表现出场诱导的缓慢弛豫O-供体轴向配体（硝酸盐）的磁化强度，但不适用于 N-供体变体（异硫氰酸盐）。实验和电子结构计算研究表明，低自旋Ni( III )的本征自旋极化受到局域配位几何和超分子相互作用的显着调节。Ni( III ) 与反磁性 Co( III ) 离子的固态稀释形成相关的复合盐，[Ni _x Co _{1− x} (cyclam)(NO ₃ ) ₂ ](NO ₃ )·2HNO ₃ (0.1 < x < 1 ），它保留了慢磁动力学，从而支持分子成分来减缓弛豫。磁弛豫寿命的初步分析最适合拉曼和直接弛豫过程的组合。