Bazhenova Tamara A, Zorina Leokadiya V, Simonov Sergey V, Mironov Vladimir S, Maximova Olga V, Spillecke Lena, Koo Changhyun, Klingeler Rüdiger, Manakin Yuriy V, Vasiliev Alexander N, Yagubskii Eduard B
Institute of Problems of Chemical Physics, RAS, Chernogolovka 142432, Russia.
Institute of Solid State Physics, RAS, Chernogolovka 142432, Russia.
Dalton Trans. 2020 Nov 10;49(43):15287-15298. doi: 10.1039/d0dt03092a.
A series of three mononuclear pentagonal-bipyramidal V(iii) complexes with the equatorial pentadentate N3O2 ligand (2,6-diacethylpyridinebis(benzoylhydrazone), H2DAPBH) in the different charge states (H2DAPBH0, HDAPBH1-, DAPBH2-) and various apical ligands (Cl-, CH3OH, SCN-) were synthesized and characterized structurally and magnetically: [V(H2DAPBH)Cl2]Cl·C2H5OH (1), [V(HDAPBH)(NCS)2]·0.5CH3CN·0.5CH3OH (2) and [V(DAPBH)(CH3OH)2]Cl·CH3OH (3). All three complexes reveal paramagnetic behavior, resulting from isolated S = 1 spins with positive zero-field splitting energy expected for the high-spin ground state of the V3+ (3d2) ion in a PBP coordination. Detailed high-field EPR measurements for compound 3 show that its magnetic properties are best described by using the spin Hamiltonian with the positive ZFS energy (D = +4.1 cm-1) and pronounced dimer-like antiferromagnetic spin coupling (J = -1.1 cm-1). Theoretical analysis based on superexchange calculations reveals that the long-range spin coupling between distant V3+ ions (8.65 Å) is mediated through π-stacking contacts between the planar DAPBH2- ligands of two neighboring [V(DAPBH)(CH3OH)2]+ complexes.
合成了一系列三种单核五角双锥型V(iii)配合物，其赤道面为五齿N3O2配体（2,6 - 二乙酰基吡啶双(苯甲酰腙)，H2DAPBH），处于不同电荷状态（H2DAPBH0、HDAPBH1-、DAPBH2-），并带有各种顶端配体（Cl-、CH3OH、SCN-），对其进行了结构和磁性表征：[V(H2DAPBH)Cl2]Cl·C2H5OH (1)、[V(HDAPBH)(NCS)2]·0.5CH3CN·0.5CH3OH (2) 和 [V(DAPBH)(CH3OH)2]Cl·CH3OH (3)。所有三种配合物都表现出顺磁行为，这是由孤立的S = 1自旋导致的，对于PBP配位中V3+（3d2）离子的高自旋基态，预期具有正的零场分裂能。对化合物3进行的详细高场EPR测量表明，使用具有正ZFS能量（D = +4.1 cm-1）和明显的二聚体状反铁磁自旋耦合（J = -1.1 cm-1）的自旋哈密顿量可以最好地描述其磁性。基于超交换计算的理论分析表明，远距离V3+离子（8.65 Å）之间的长程自旋耦合是通过两个相邻的[V(DAPBH)(CH3OH)2]+配合物的平面DAPBH2-配体之间的π堆积接触介导的。
