El-Khatib Fatima, Cahier Benjamin, López-Jordà Maurici, Guillot Régis, Rivière Eric, Hafez Hala, Saad Zeinab, Girerd Jean-Jacques, Guihéry Nathalie, Mallah Talal
Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris Sud, CNRS , Université Paris Saclay, 91405 Orsay Cedex, France.
Lebanese University, Inorganic & Environmental Chemistry Laboratory, Faculty of Sciences I, Hadath, Lebanese University , Beirut, Lebanon.
Inorg Chem. 2017 Sep 5;56(17):10655-10663. doi: 10.1021/acs.inorgchem.7b01609. Epub 2017 Aug 23.
The preparation of a binuclear Ni(II) complex with a pentacoordinate environment using a cryptand organic ligand and the imidazolate bridge is reported. The coordination sphere is close to trigonal bipyramidal (tbp) for one Ni(II) and to square pyramidal (spy) for the other. The use of the imidazolate bridge that undergoes π-π stacking with two benzene rings of the chelating ligand induces steric hindrance that stabilizes the pentacoordinate environment. Magnetic measurements together with theoretical studies of the spin states energy levels allow fitting the data and reveal a large Ising-type anisotropy and a weak anti-ferromagnetic exchange coupling between the metal ions. The magnitude and the nature of the magnetic anisotropy and the difference in anisotropy between the two metal ions are rationalized using wave-function-based calculations. We show that a slight distortion of the coordination sphere of Ni(II) from spy to tbp leads to an Ising-type anisotropy. Broken-symmetry density functional calculations rationalize the weak anti-ferromagnetic exchange coupling through the imidazolate bridge.
报道了使用穴状配体和咪唑桥制备具有五配位环境的双核镍（II）配合物。其中一个镍（II）的配位球接近三角双锥（tbp），另一个接近四方锥（spy）。咪唑桥与螯合配体的两个苯环发生π-π堆积，产生空间位阻，从而稳定了五配位环境。磁性测量以及自旋态能级的理论研究能够拟合数据，并揭示出较大的伊辛型各向异性以及金属离子之间微弱的反铁磁交换耦合。利用基于波函数的计算对磁各向异性的大小和性质以及两种金属离子之间各向异性的差异进行了合理解释。我们表明，镍（II）的配位球从四方锥轻微扭曲为三角双锥会导致伊辛型各向异性。破缺对称性密度泛函计算通过咪唑桥对微弱的反铁磁交换耦合进行了合理解释。
