Zhao Sheng-Ze, Qin Chun-Yan, Wang Shi, Yamashita Masahiro, Li Yong-Hua, Huang Wei
Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Jiangsu National Synergistic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, Nanjing 210023, China.
Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
Dalton Trans. 2020 Apr 7;49(14):4293-4305. doi: 10.1039/c9dt04882k.
This paper reports the syntheses, crystal structures and magnetic properties of spin crossover (SCO) salts of formulae [Mn(naphth-sal-N-1,5,8,12)]SbF6 (1), [Mn(naphth-sal-N-1,5,8,12)]AsF6 (2), [Mn(naphth-sal-N-1,5,8,12)]PF6·1/2CH3OH (3) and [Mn(naphth-sal-N-1,5,8,12)]ClO4 (4), where (naphth-sal-N-1,5,8,12)2- (2,2'-((1E,14E)-2,6,10,14-tetraazapentadeca-1,14-diene-1,15-diyl)diphenolate) is a big conjugated hexadentate Schiff-base ligand. Magnetic susceptibility measurements demonstrated that complexes 1 and 2 showed a gradual one-step SCO between the high-spin (HS, S = 2) and low-spin (LS, S = 1) states without thermal hysteresis. The transition temperatures T1/2 of the SbF6 (1) and AsF6 (2) salts estimated from the magnetic susceptibility measurements are 164 and 171 K, respectively. The existence of the crystal solvent of complex 3 changes the supramolecular packing, leading to close ππ stacking interactions between the phenyl groups of the ligands. These close stacking interactions hinder the flexibility of the whole ligand, precluding the spin transformation of complex 3 and leading to its stabilization in the HS state in the temperature range of 2-300 K. For 4, crystal structure analysis indicates that the reduction in the anion size leads to close contacts between the naphthalene rings. These C-Hπ interactions provide a means for preventing the spin crossover occurring at low temperatures.
本文报道了化学式为[Mn(naphth-sal-N-1,5,8,12)]SbF6 (1)、[Mn(naphth-sal-N-1,5,8,12)]AsF6 (2)、[Mn(naphth-sal-N-1,5,8,12)]PF6·1/2CH3OH (3)和[Mn(naphth-sal-N-1,5,8,12)]ClO4 (4)的自旋交叉（SCO）盐的合成、晶体结构及磁性质，其中(naphth-sal-N-1,5,8,12)2-（2,2'-((1E,14E)-2,6,10,14-四氮杂十五碳-1,14-二烯-1,15-二基)二酚盐）是一种大的共轭六齿席夫碱配体。磁化率测量表明，配合物1和2在高自旋（HS，S = 2）和低自旋（LS，S = 1）态之间呈现逐渐的一步自旋交叉，且无热滞现象。通过磁化率测量估算的SbF6 (1)和AsF6 (2)盐的转变温度T1/2分别为164 K和171 K。配合物3的晶体溶剂的存在改变了超分子堆积，导致配体苯环之间存在紧密的ππ堆积相互作用。这些紧密的堆积相互作用阻碍了整个配体的灵活性，排除了配合物3的自旋转变，并使其在2 - 300 K的温度范围内稳定在HS态。对于4，晶体结构分析表明阴离子尺寸的减小导致萘环之间紧密接触。这些C-Hπ相互作用提供了一种防止在低温下发生自旋交叉的方法。
