Ligand directed self-assembly vs. metal ion coordination algorithm—when does the ligand or the metal take control?
作者:Konstantin V. Shuvaev、Tareque S. M. Abedin、Corey A. McClary、Louise N. Dawe、Julie L. Collins、Laurence K. Thompson
DOI:10.1039/b818939k
日期:——
Polyfunctional hydrazone ligands with multidentate terminal donor groups offer metal ions many donor choices, and the coordination outcome depends mainly on the identity of the metal ion. Co(II) and Ni(II) prefer to adopt largely undistorted, six-coordinate geometries, while Cu(II) can easily adapt to a variety of coordination situations (e.g. CN 4â6), and will optimize its coordination number and stereochemistry based on all the available donors. Ni(II) and Co(II) form simple [2 à 2] [M4-(μ2-O)4] square grids with such ditopic hydrazone ligands, and ignore other coordination options, while Cu(II) tries to bind to all the available donors, and forms extended and 2D structures based on linked Cu(II) triads rather than grids. Ni(II) is also reluctant to compromise its desire to maximize its crystal field stabilization energy (CFSE) by binding to âweakâ ligands, and with a tetratopic pyrazole bis-hydrazone ligand it ignores the oxygen donors in favour of nitrogen, forming a novel trinuclear, triangular cluster. Also, reaction of a linear Ni(II)3 complex of a tetratopic pyridazine bis-hydrazone ligand with NiN6 coordination spheres with Cu(II), leads exclusively to a square Cu12 grid based complex, and complete displacement of nickel. Structural and magnetic properties are highlighted, and metalâligand interactions are discussed in detail.
多官能腙配体具有多个末端供体基团,可为金属离子提供多种供体选择,配位结果主要取决于金属离子的特性。Co(II)和 Ni(II)喜欢采用基本不变形的六配位几何结构,而 Cu(II) 则很容易适应各种配位情况(如 CN 4â6),并会根据所有可用的供体优化其配位数和立体化学结构。Ni(II) 和 Co(II) 与这类二价腙配体形成简单的 [2 à 2] [M4-(μ2-O)4] 方格,而忽略了其他配位选择,而 Cu(II) 则试图与所有可用的供体结合,并基于相连的 Cu(II) 三元组而不是方格形成扩展的二维结构。镍(II)也不愿意因为与 "弱 "配体结合而损害其最大化晶场稳定能(CFSE)的愿望,在与四位吡唑双腙配体结合时,它忽略了氧供体而选择了氮,形成了一种新颖的三核三角形团簇。此外,四位哒嗪双腙配体与 NiN6 配位球的线性 Ni(II)3 复合物与铜(II)反应,只能生成基于 Cu12 网格的方形复合物,镍完全置换。报告重点介绍了该复合物的结构和磁性,并详细讨论了金属与配体之间的相互作用。