A series of heterometallic [TiIV7MIII] rings are reported which contain a single paramagnetic metal centre, either FeIII or CrIII. The structures contain an octagon of metals bridged by oxides within the ring and pivalate ligands outside the ring. The structures encapsulate a single cation, either a secondary ammonium cation or a cesium. Multi-frequency EPR spectroscopy was used to measure the zero-field splitting parameters for the paramagnetic metal sites. The FeIII sites have rhombic anisotropy, with D around − 0.18 cm−1 and λ (= D/E) approximately 0.25. The CrIII have a more axial anisotropy, with D around − 0.5 cm−1 and λ around 0.05. Attempts to find a magneto-structural correlation are vitiated by the difficulty of refining the challenging crystal structures.

中文翻译：

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CrIII 和 FeIII 在一系列 {Ti7M} 环中的单离子各向异性

据报道，一系列异金属 [TiIV7MIII] 环包含单个顺磁性金属中心，FeIII 或 CrIII。该结构包含由环内的氧化物和环外的新戊酸酯配体桥接的八边形金属。这些结构封装了一个单一的阳离子，要么是仲铵阳离子，要么是铯。多频EPR光谱用于测量顺磁金属位点的零场分裂参数。FeIII 位点具有菱形各向异性，D 约为 − 0.18 cm-1，λ (= D/E) 约为 0.25。CrIII 具有更大的轴向各向异性，D 约为 - 0.5 cm-1，λ 约为 0.05。由于难以精炼具有挑战性的晶体结构，试图找到磁结构相关性的努力失败了。