Kulyabin Pavel S, Goryunov Georgy P, Iashin Andrei N, Mladentsev Dmitry Y, Uborsky Dmitry V, Ehm Christian, Canich Jo Ann M, Hagadorn John R, Voskoboynikov Alexander Z
Department of Chemistry, M. V. Lomonosov Moscow State University Leninskie Gory, 1/3 Moscow 119991 Russian Federation.
Dipartimento di Scienze Chimiche, Università di Napoli Federico II Via Cintia Napoli 80126 Italy.
Chem Sci. 2024 Aug 27;15(38):15825-34. doi: 10.1039/d4sc02173h.
Pyridylamides of zirconium and hafnium with [C,N,N]-ligands reversibly insert nitriles into M-C bonds leading to an observable equilibrium between the starting [C,N,N]-complexes and newly formed [N,N,N]-complexes with a ketimide moiety in a 7-membered metallacycle. The discovered reversible insertion of nitriles into M-C bonds represents an unprecedented example of β-aryl elimination from a ketimide ligand in early transition metal complexes. Experimental and computational studies suggest thermodynamic and electronic reasons for this reactivity. Weak orbital overlap between the ketimide nitrogen and the metal, and an unfavorable 7-membered metallacycle destabilize the product of insertion into the M-C bond, while the pyridylamide moiety acts as a directing group making the reverse process viable. The influence of non-chelate spectator ligands on the metal center and substituents in nitrile on the thermodynamic stability of the [N,N,N]-complexes was also studied. Exploiting β-carbon elimination in complexes of early transition metals may extend the range of catalysts that are accessible for C-C activation processes in the future.
锆和铪与[C,N,N]配体形成的吡啶酰胺可将腈可逆地插入M-C键，导致起始的[C,N,N]配合物与新形成的在七元金属环中带有酮亚胺部分的[N,N,N]配合物之间达到可观察到的平衡。所发现的腈向M-C键的可逆插入代表了早期过渡金属配合物中酮亚胺配体β-芳基消除的一个前所未有的例子。实验和计算研究表明了这种反应性的热力学和电子学原因。酮亚胺氮与金属之间的弱轨道重叠以及不利的七元金属环使插入M-C键的产物不稳定，而吡啶酰胺部分作为导向基团使逆过程可行。还研究了非螯合旁观配体对金属中心的影响以及腈中的取代基对[N,N,N]配合物热力学稳定性的影响。利用早期过渡金属配合物中的β-碳消除可能会扩展未来可用于C-C活化过程的催化剂范围。
