Kühne Irina A, Barker Andrew, Zhang Fengyuan, Stamenov Plamen, O'Doherty Oisín, Müller-Bunz Helge, Stein Matthias, Rodriguez Brian J, Morgan Grace G
School of Chemistry, University College Dublin (UCD), Dublin, Ireland.
School of Physics and Conway Institute of Biomolecular and Biomedical Research, University College Dublin (UCD), Dublin, Ireland.
J Phys Condens Matter. 2020 Jul 3;32(40). doi: 10.1088/1361-648X/ab82d1.
Structural, magnetic and electromechanical changes resulting from spin crossover between the spin quintet and spin triplet forms of a mononuclear Mncomplex embedded in six lattices with different charge balancing counterions are reported. Isostructural ClOand BFsalts () and () each have two unique Mnsites which follow different thermal evolution pathways resulting in a crossover from the spin quintet form at room temperature to a 1:1 spin triplet:quintet ratio below 150 K. The PF() and NO() salts which each have one unique Mnsite show a complete conversion from spin quintet to spin triplet over the same temperature range. A complete two step spin crossover is observed in the CFSOlattice () with a 1:1 ratio of spin quintet and spin triplet forms at intermediate temperature, while the BPhlattice () stabilizes the spin triplet form over most of the temperature range with gradual and incomplete spin state switching above 250 K. An electromechanical piezoresponse was detected in NOcomplexdespite crystallization in a centrosymmetric space group. The role of deformations associated with stress-induced spin triplet-spin quintet switching in breaking the local symmetry are discussed and computational analysis is used to estimate the energy gap between the two spin states.
报道了嵌入六种具有不同电荷平衡抗衡离子晶格中的单核锰配合物，在自旋五重态和自旋三重态形式之间发生自旋交叉所导致的结构、磁性和机电变化。同构的ClO盐和BF盐（）和（）各有两个独特的锰位点，它们遵循不同的热演化路径，导致从室温下的自旋五重态形式转变为低于150 K时1:1的自旋三重态:五重态比例。PF盐（）和NO盐（）各有一个独特的锰位点，在相同温度范围内显示出自旋五重态到自旋三重态的完全转变。在CFSO晶格（）中观察到完整的两步自旋交叉，在中间温度下自旋五重态和自旋三重态形式的比例为1:1，而BPh晶格（）在大部分温度范围内稳定自旋三重态形式，在250 K以上有逐渐且不完全的自旋态转换。尽管在中心对称空间群中结晶，但在NO配合物中检测到了机电压阻响应。讨论了与应力诱导的自旋三重态 - 自旋五重态转换相关的变形在打破局部对称性中的作用，并使用计算分析来估计两个自旋态之间的能隙。
