State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China.
Jiangsu Key Laboratory of Biofunctional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing, 210023, China.
Dalton Trans. 2023 May 2;52(17):5575-5586. doi: 10.1039/d3dt00610g.
Three new cyanide-bridged compounds {[Mn((,)-Dpen)][Mn((,)-Dpen)(HO)][Mo(CN)]·4HO·4CHN} (1-SS), {[Mn((,)-Dpen)][Mn((,)-Dpen)(HO)][Mo(CN)]·4.5HO·4CHN} (1-RR), and {[Mn(Chxn)][Mn(Chxn)(HO)][Mo(CN)]·HO·4CHN} (2) (/-Dpen = (,)/(,)-1,2-diphenylethylenediamine and Chxn = 1,2-cyclohexanediamine) have been successfully synthesized from the self-assembly reaction of the [Mo(CN)] unit, the Mn ions, and two chiral bidentate chelating ligands. Single-crystal structure determinations show that compounds 1-SS and 1-RR containing ligands /-Dpen are enantiomers and crystallize in the chiral space group 2. On the other hand, compound 2 crystallizes in the achiral centrosymmetric space group 1̄ due to the racemization of the /-Chxn ligands during the growth of the crystals. Despite their different space groups and ligands, all three compounds exhibit similar framework structures consisting of cyano-bridged Mn-Mo two-dimensional layers separated by the bidentate ligands. The circular dichroism (CD) spectra have further demonstrated the enantiopure character of compounds 1-SS and 1-RR. Magnetic measurements revealed that all three compounds display ferrimagnetic ordering with similar critical temperatures of about 40 K. The chiral enantiomers 1-SS and 1-RR exhibit the magnetic hysteresis loop with a coercive field of about 8000 Oe at 2 K, which is by far the highest for all known Mn-[Mo(CN)] magnets. Analyses of their structures and magnetic properties indicated that their magnetic properties depend on the anisotropic magnetic interactions between the Mn and Mo centers, which are closely related to the C-N-M bond angles.
三种新的氰桥化合物{[Mn((,)-Dpen)][Mn((,)-Dpen)(HO)][Mo(CN)]·4HO·4CHN}（1-SS），{[Mn((,)-Dpen)][Mn((,)-Dpen)(HO)][Mo(CN)]·4.5HO·4CHN}（1-RR）和{[Mn(Chxn)][Mn(Chxn)(HO)][Mo(CN)]·HO·4CHN}（2）（/-Dpen = (,)/(,)-1,2-二苯乙二胺和 Chxn = 1,2-环己二胺）已成功地通过自组装反应的[Mo(CN)]单元，Mn 离子和两个手性双齿螯合配体合成。单晶结构测定表明，含有配体/-Dpen 的化合物 1-SS 和 1-RR 是对映异构体，并结晶在手性空间群 2 中。另一方面，化合物 2 由于在晶体生长过程中/-Chxn 配体的外消旋化，结晶在非手性中心对称空间群 1̄中。尽管它们的空间群和配体不同，但所有三种化合物都表现出相似的框架结构，由氰桥接的 Mn-Mo 二维层组成，由双齿配体隔开。圆二色（CD）光谱进一步证明了化合物 1-SS 和 1-RR 的对映纯性质。磁性测量表明，所有三种化合物都表现出铁磁有序，临界温度约为 40 K。手性对映异构体 1-SS 和 1-RR 在 2 K 时表现出具有约 8000 Oe 的矫顽场的磁滞回线，这是迄今为止所有已知的 Mn-[Mo(CN)]磁体中最高的。对它们的结构和磁性的分析表明，它们的磁性性质取决于 Mn 和 Mo 中心之间的各向异性磁相互作用，这与 C-N-M 键角密切相关。
