Kelly Conor T, Griffin Michael, Esien Kane, Felton Solveig, Müller-Bunz Helge, Morgan Grace G
School of Chemistry, University College Dublin, Belfield, Dublin 4D04 N2E5, Ireland.
School of Mathematics and Physics, Queen's University Belfast, BelfastBT7 1NN, United Kingdom.
Cryst Growth Des. 2022 Nov 2;22(11):6429-6439. doi: 10.1021/acs.cgd.2c00468. Epub 2022 Oct 17.
We report a single example of thermal spin crossover in a series of Fe complexes, [Fe(R-sal323)], which typically stabilize the low-spin ( = 1/2) state. Single-crystal X-ray diffraction analysis of 53 such complexes with varying "R" groups, charge-balancing anions, and/or lattice solvation confirms bond lengths in line with an = 1/2 ground state, with only the [Fe(4-OMe-sal323)]NO complex () exhibiting longer bond lengths associated with a percentage of the spin sextet form at room temperature. Structural distortion parameters are investigated for the series. A magnetic susceptibility measurement of reveals a gradual, incomplete transition, with = 265 K in the solid state, while Evans method NMR reveals that the sample persists in the low-spin form in solution at room temperature. Computational analysis of the spin state preferences for the cations [Fe(4-OMe-sal323)] and [Fe(sal323)] confirmed the energetic preference for the spin doublet form in both, and the thermal spin crossover in complex is therefore attributed to perturbation of the crystal packing on warming.
我们报道了一系列铁配合物[Fe(R-sal323)]中热自旋交叉的一个单一实例，这些配合物通常稳定低自旋（S = 1/2）态。对53个具有不同“R”基团、电荷平衡阴离子和/或晶格溶剂化的此类配合物进行单晶X射线衍射分析，证实键长与S = 1/2基态一致，只有[Fe(4-OMe-sal323)]NO配合物（）在室温下表现出与一定比例的自旋六重态形式相关的较长键长。对该系列的结构畸变参数进行了研究。对的磁化率测量显示出逐渐的、不完全的转变，固态时T1/2 = 265 K，而埃文斯方法核磁共振显示该样品在室温下在溶液中保持低自旋形式。对阳离子[Fe(4-OMe-sal323)]和[Fe(sal323)]的自旋态偏好进行的计算分析证实了两者对自旋二重态形式的能量偏好，因此配合物中的热自旋交叉归因于升温时晶体堆积的扰动。
