Institutes of Physical Science and Information Technology, College of Chemistry and Chemical Engineering, Anhui University, Hefei, 230601, People's Republic of China.
Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials, Key Laboratory of Structure and Functional Regulation of Hybrid Materials (Anhui University), Ministry of Education, Hefei, 230601, People's Republic of China.
Dalton Trans. 2022 Jun 27;51(25):9699-9707. doi: 10.1039/d2dt01282k.
Tetradentate NS coordination platforms are widespread in biological systems and have endowed metalloenzymes and metalloproteins with abundant reactivities and functions. However, there are only three types of NS scaffolds respectively based on the bipyridine, aryl and alkyl amine derivatives, which are significantly underdeveloped for coordination chemistry. With the objective of developing a new NS coordination platform to assemble a series of first-row transition metal complexes, we have designed a novel tetradentate NS ligand containing a central dipyrrin donor functionalized with two thioether-substituted aryl units. Interestingly, complexation of the NS ligand with the chloride salts of Ni(II), Cu(II) and Zn(II) yields various geometries with various coordination numbers. The reaction between the ligand and NiCl readily forms two chloride-bridged centrosymmetric dinickel complexes in which the nickel centers are hexacoordinated by an NSCl coordination environment in distorted octahedron geometry. In contrast, metalation of the ligand with CuCl gives a mononuclear copper complex consisting of a pentacoordinated copper center in a trigonal bipyramidal geometry with an NSCl coordination sphere. Unexpectedly, the complexation of the ligand with ZnCl forms a homoleptic zinc complex in which the zinc center is surrounded by an N coordination sphere from two dipyrrin units in a non-planar pseudo-tetrahedral geometry despite the steric hindrance of two bulk thioether-substituted aryl units. These various geometries illustrate the potential structural flexibility of this new ligand. In addition, the optical properties of these compounds were also examined. This work thus provides a new NS coordination platform with geometric flexibility.
四齿配位的 NS 配位平台在生物体系中广泛存在，赋予了金属酶和金属蛋白丰富的反应性和功能。然而，基于联吡啶、芳基和烷基胺衍生物的 NS 支架只有三种类型，在配位化学中明显不够发达。为了开发一种新的 NS 配位平台来组装一系列第一过渡金属络合物，我们设计了一种新型的四齿 NS 配体，其中央二吡咯供体上功能化有两个硫醚取代的芳基单元。有趣的是，NS 配体与 Ni(II)、Cu(II)和 Zn(II)的氯化物盐的络合形成了具有不同配位数的各种几何形状。配体与 NiCl 的反应容易形成两个中心对称的二镍络合物，其中镍中心通过 NSCl 配位环境在扭曲的八面体几何中六配位。相比之下，配体与 CuCl 的金属化形成一个单核铜络合物，由五配位的铜中心在三角双锥几何中与 NSCl 配位球组成。出乎意料的是，配体与 ZnCl 的络合形成一个同核锌络合物，其中锌中心被来自两个二吡咯单元的 N 配位球包围，形成非平面的拟四面体几何，尽管存在两个体积庞大的硫醚取代芳基单元的空间位阻。这些不同的几何形状说明了这种新配体的潜在结构灵活性。此外，还研究了这些化合物的光学性质。这项工作因此提供了一种具有几何灵活性的新 NS 配位平台。
