A computational study of the spin-crossover behavior in the family [(Cp^R)₂Mn] (R = Me, ⁱPr, ^tBu) is presented. Using the OPBE functional, the different electronic and steric effects over the metal’s ligand field are studied, and trends in the spin-crossover-temperature (T_1/2) behavior are presented in terms of the cyclopentadienyl (Cp) ligand functionalization. Our calculations outlined a delicate balance between both electronic and steric effects. While an increase in the number of electron-donating groups increases the spin-crossover temperature (T_1/2) to the point that the transition is suppressed and only the low-spin state is observed, steric effects play an opposite role, increasing the distance between the Cp rings, which in turns shifts T_1/2 to lower values, eventually stabilizing the high-spin state. Both effects can be rationalized by exploring the electronic structure of such systems in terms of the relevant d-based molecular orbitals.

中文翻译：

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[（Cp ^R）₂ Mn]锰合金自旋交叉行为的电子和立体控制

提出了对[[Cp ^R）₂ Mn]（R = Me，ⁱ Pr，^t Bu）族中自旋交叉行为的计算研究。使用OPBE官能团，研究了金属配体场上的不同电子和空间效应，并根据环戊二烯基（Cp）配体官能化提出了自旋交叉温度（T _1/2）行为的趋势。我们的计算概述了电子效果和空间效果之间的微妙平衡。给电子基团数量的增加会增加自旋交叉温度（T _1/2）到抑制转变并仅观察到低旋转状态的程度，空间效应起相反的作用，增加了Cp环之间的距离，进而将T _1/2移至较低的值，最终稳定了高的旋转状态。可以通过根据相关的基于d的分子轨道探索此类系统的电子结构来合理化这两种效应。