Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, and INSTM RU of Modena and Reggio Emilia, via G. Campi 103, 41125, Modena, Italy.
Current address: Laboratoire Interfaces Traitements Organisation, et Dynamique des Systèmes (ITODYS), UMR 7086 CNRS, Université Paris 7 Diderot, Paris Bât. Lavoisier, 15 rue Jean-Antoine de Baïf, 75205, Paris Cedex 13, France.
Chemistry. 2018 Jun 21;24(35):8857-8868. doi: 10.1002/chem.201801026. Epub 2018 May 30.
The homoleptic mononuclear compound Co(bpp-COOMe) (1) (bpp-COOMe=methyl 2,6-di(pyrazol-1-yl)pyridine-4-carboxylate) crystallizes in the monoclinic C2/c space group, and the cobalt(II) ion possesses a pseudo-octahedral environment given by the two mer-coordinated tridentate ligands. Direct-current magnetic data, single-crystal torque magnetometry, and EPR measurements disclosed the easy-axis nature of this cobalt(II) complex, which shows single-molecule magnet behavior when a static field is applied in alternating-current susceptibility measurements. Diamagnetic dilution in the zinc(II) analogue Zn(bpp-COOMe) (2) afforded the derivative Zn Co (bpp-COOMe) (3), which exhibits slow relaxation of magnetization even in zero field thanks to the reduction of dipolar interactions. Theoretical calculations confirmed the overall electronic structure and the magnetic scenario of the compound as drawn by experimental data, thus confirming the spin-phonon Raman relaxation mechanism, and a direct quantum tunneling in the ground state as the most plausible relaxation pathway in zero field.
具有假八面体配位环境的单核配合物 Co(bpp-COOMe) (1) (bpp-COOMe=甲基 2,6-二(吡唑-1-基)吡啶-4-羧酸酯)，以单斜 C2/c 空间群结晶。钴（II）离子由两个处于对位的三齿配体提供，呈现出假八面体配位环境。直流磁数据、单晶扭转磁强计和 EPR 测量揭示了该钴（II）配合物的易轴性质，在交流磁化率测量中施加静态磁场时，其表现出单分子磁体行为。在锌（II）类似物 Zn(bpp-COOMe) (2)中进行的抗磁性稀释得到了衍生物 Zn Co (bpp-COOMe) (3)，由于偶极相互作用的降低，即使在零场中，该衍生物也表现出缓慢的磁化弛豫。理论计算证实了实验数据所描绘的化合物的整体电子结构和磁情况，从而证实了自旋-声子 Raman 弛豫机制以及在零场中基态的直接量子隧道作为最可能的弛豫途径。
