Mathivathanan Logesh, Rogez Guillaume, Ben Amor Nadia, Robert Vincent, Raptis Raphael G, Boudalis Athanassios K
Department of Chemistry and Biochemistry and, the Biomolecular Sciences Institute, Florida International University, Miami, FL, 33199, USA.
Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), CNRS/Université de Strasbourg, UMR 7504, 67000, Strasbourg, France.
Chemistry. 2020 Oct 6;26(56):12769-12784. doi: 10.1002/chem.202001028. Epub 2020 Sep 4.
Previously reported ferromagnetic triangles (NnBu ) [Cu (μ -Cl) (μ-4-NO -pz) Cl ] (1), (PPN) [Cu (μ -Cl) (μ-pz) Cl ] (2), (bmim) [Cu (μ -Cl) (μ-pz) Cl ] (3) and newly reported (PPh ) [Cu (μ -Cl) (μ-4-Ph-pz) Cl ] (4) were studied by magnetic susceptometry, electron paramagnetic resonance (EPR) spectroscopy and ab initio calculations to assess the origins of their ferromagnetism and of the magnetic anisotropy of their ground S=3/2 state (PPN =bis(triphenylphosphine)iminium, bmim =1-butyl-3-methylbenzimidazolium, pz =pyrazolate). Ab initio studies revealed the d character of the magnetic orbitals of the compressed trigonal bipyramidal copper(II) ions. Ferromagnetic interactions were attributed to weak orbital overlap via the pyrazolate bridges. From the wavefunctions expansions, the ratios of the magnetic couplings were determined, which were indeterminate by magnetic susceptometry. Single-crystal EPR studies of 1 were carried out to extend the spin Hamiltonian with terms which induce zero-field splitting (zfs), namely dipolar interactions, anisotropic exchange and Dzyaloshinskii-Moriya interactions (DMI). The data were treated through both a giant-spin model and through a multispin exchange-coupled model. The latter indicated that ≈62 % of the zfs is due to anisotropic and ≈38 % due to dipolar interactions. The powder EPR data of all complexes were fitted to a simplified form of the multispin model and the anisotropic and dipolar contributions to the ground state zfs were estimated.
先前报道的铁磁三角形化合物（NnBu）[Cu（μ-Cl）（μ-4-NO₂-pz）Cl]（1）、（PPN）[Cu（μ-Cl）（μ-pz）Cl]（2）、（bmim）[Cu（μ-Cl）（μ-pz）Cl]（3）以及新报道的（PPh₃）[Cu（μ-Cl）（μ-4-Ph-pz）Cl]（4），通过磁导率测量、电子顺磁共振（EPR）光谱和从头算计算进行了研究，以评估它们铁磁性的起源以及基态S = 3/2态的磁各向异性（PPN = 双（三苯基膦）亚胺鎓，bmim = 1-丁基-3-甲基苯并咪唑鎓，pz = 吡唑酸根）。从头算研究揭示了压缩三角双锥铜（II）离子磁轨道的d特性。铁磁相互作用归因于通过吡唑酸根桥的弱轨道重叠。从波函数展开式中确定了磁耦合的比率，这在磁导率测量中是不确定的。对1进行了单晶EPR研究，以扩展自旋哈密顿量，加入诱导零场分裂（zfs）的项，即偶极相互作用、各向异性交换和Dzyaloshinskii-Moriya相互作用（DMI）。数据通过巨自旋模型和多自旋交换耦合模型进行处理。后者表明，≈62%的zfs归因于各向异性，≈38%归因于偶极相互作用。将所有配合物的粉末EPR数据拟合到多自旋模型的简化形式，并估计了基态zfs的各向异性和偶极贡献。
