Criteria for a technologically relevant spin crossover (SCO) material include temperature and abruptness. A series of Fe(II) – 1,3-bis((1H-tetrazol-1-yl)methyl)bicyclo[1.1.1]pentane SCO complexes with various anions (BF₄⁻, ClO₄⁻, and PF₆⁻) designed using a structure–property based concept is reported. All complexes feature abrupt SCO-behavior with T_1/2 between 170 K and 187 K. These materials demonstrate that without stabilizing the effects of incorporated solvents or a hydrogen bond-network, the observed cooperativity during high-spin–low-spin transition is anion independent and originates only from the rigidity and internal strain of the propellane-moiety in the ligand. Spectroscopy and structural investigations of these materials are supported by quantum chemical calculations.

中文翻译：

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自旋交联材料中配位体的协同作用– Fe（ii）– 1,3-双（（1 H-四唑-1-基）甲基）双环[1.1.1]戊烷体系的研究†

与技术相关的自旋交联（SCO）材料的标准包括温度和突变率。一系列的Fe（II） - 1,3-双（（1 ħ -四唑-1-基）甲基）二环[1.1.1]戊烷SCO络合物与各种阴离子（BF ₄ ^-，CLO ₄ ^-和PF ₆ ^-）报告了使用基于结构属性的概念设计的。所有复合体均具有T _1/2的突然SCO行为在170 K和187 K之间。这些材料表明，在不稳定所掺入溶剂或氢键网络的影响的情况下，在高旋-低旋转变过程中观察到的协同性与阴离子无关，并且仅源自于其刚性和内部应变。配体中的炔丙基部分。这些材料的光谱学和结构研究得到了量子化学计算的支持。