Structure–function correlations in mononuclear manganese(III) spin crossover systems with a big conjugated hexadentate Schiff-base ligand,Dalton Transactions

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Structure–function correlations in mononuclear manganese(III) spin crossover systems with a big conjugated hexadentate Schiff-base ligand
Dalton Transactions ( IF 3.5 ) Pub Date : 2020/03/03 , DOI: 10.1039/c9dt04882k
Sheng-Ze Zhao _{1,

2,

3,

4,

5} , Chun-Yan Qin _{1,

2,

3,

4,

5} , Shi Wang _{1,

2,

3,

4,

5} , Masahiro Yamashita _{6,

7,

8,

9,

10} , Yong-Hua Li _{1,

2,

3,

4,

5} , Wei Huang _{1,

2,

3,

4,

5}

Affiliation

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 T_1/2 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 π⋯π 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–H⋯π interactions provide a means for preventing the spin crossover occurring at low temperatures.

中文翻译：

具有大共轭六齿席夫碱配体的单核锰（III）自旋交联系统的结构-功能相关性

本文报道了分子式为[Mn（naphth -sal - N -1,5,8,12）] SbF ₆（1），[Mn（naphth-sal ）的自旋交叉（SCO）盐的合成，晶体结构和磁性- ñ -1,5,8,12）] ASF ₆（2），[锰（萘sal- ñ -1,5,8,12）] PF ₆ ·1 / 2CH ₃ OH（3）和[锰（naphth-sal- N -1,5,8,12）] ClO ₄（4），其中（naphth-sal- N -1,5,8,12）^2-（2,2'-（（1 E，14 E）-2,6,10,14-四氮杂pentadeca-1,14-二烯-1,15-二基）二酚盐）是一个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）状态之间显示逐步的单步SCO，没有热滞后。根据磁化率测量估计的SbF ₆（1）和AsF ₆（2）盐的转变温度T _1/2分别为164 K和171K。配合物3的晶体溶剂的存在改变超分子堆积，导致配体的苯基之间紧密的π⋯π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柔性，阻止了配合物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，阴离子的大小会导致萘环之间紧密接触。这些C–H⋯π相互作用提供了防止在低温下发生自旋交叉的方法。

更新日期：2020-04-08

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