Terlecki Michał, Justyniak Iwona, Leszczyński Michał K, Bernatowicz Piotr, Lewiński Janusz
Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland.
Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
Dalton Trans. 2023 Feb 28;52(9):2712-2721. doi: 10.1039/d2dt03722j.
Despite various applications of alkylzinc complexes supported by ,-bidentate ligands in chemistry and materials science, the corresponding organozinc amidinates still represent an insufficiently explored area. To gain a more in-depth understanding of factors controlling the structure and stability of alkylzinc amidinates, we selected benzamidinate and ,'-diphenylformamidinate ligands as model ,'-unsubstituted and ,'-diaryl substituted ligands, respectively, to systematically modify the secondary coordination sphere of the Zn center. A series of new alkylzinc amidinates has been synthesized and their molecular structures identified in both the solid state (single-crystal X-ray crystallography) and solution (NMR and FTIR spectroscopy). The results indicate that [RZnL]-type amidinate moieties are essentially unstable and tend to undergo Schlenk equilibria-mediated ligand scrambling leading to more thermodynamically stable non-stoichiometric [RZnL]- and [RZnL]-type complexes. This process is significantly influenced by the secondary coordination sphere noncovalent interactions as well as the steric hindrance provided by both zinc-bounded alkyl groups and the -substituents.
尽管由双齿配体支撑的烷基锌配合物在化学和材料科学中有各种应用，但相应的有机锌脒仍然是一个研究不足的领域。为了更深入地了解控制烷基锌脒结构和稳定性的因素，我们分别选择苯甲脒和二苯基甲脒配体作为模型，即未被取代的双齿配体和二芳基取代的双齿配体，以系统地修饰锌中心的二级配位层。我们合成了一系列新的烷基锌脒，并通过固态（单晶X射线晶体学）和溶液（核磁共振和傅里叶变换红外光谱）确定了它们的分子结构。结果表明，[RZnL]型脒部分本质上是不稳定的，倾向于通过施伦克平衡介导的配体重排，形成热力学上更稳定的非化学计量的[RZnL]型和[RZnL]型配合物。这个过程受到二级配位层非共价相互作用以及锌键合的烷基和取代基提供的空间位阻的显著影响。
