过渡金属催化有机腈和叠氮酸钠反应机理的研究

Studies on the Mechanism of the Transition Metal-Catalyzed Reaction of Organonitrile with Sodium Azide

过渡金属催化有机腈和叠氮酸钠反应机理的研究一直是一个具有挑战性的课题.本工作组合理论和实验方法,对其反应机理作了深入的探讨.基于对两种类型中间体(H2O)3M…N3^-和(H2O)3M…NCCH3稳定性的理论分析和中间体Cd2(μ3-N3)(μ3-OH)(μ5-CHDA)(1)和Cd(μ2-N3)(μ3-IBA)(2)(H2CHDA为1,3-环己二酸,HIBA为4'-(咪唑-1-基)苯甲酸)的成功捕获,首次从实验和理论上揭示了过渡金属离子在反应中起活化叠氮酸根的作用.此外,基于中间体(H2O)3M…N3^-和乙腈分子的静电势盆分析的结果,揭示了叠氮酸根未配位的端基N原子可以进攻氰基N原子发生加成反应,随后可能发生环加成反应生成四唑,在水分子的辅助下,其加成物也可能发生类似于里特反应生成全氮阴离子.该项研究把过渡金属催化有机腈和叠氮酸钠反应引入全氮阴离子合成的新领域.

The study on the reaction mechanism of organonitrile and sodium azide catalyzed by transition metals has always been a challenging and controversial task.Due to the difficulty in capturing the reaction intermediates,there is still no direct evidence to uncover the nature of the reaction.In this paper,the reaction mechanism has been explored by using a combining theoretical and experimental method.Based on the theoretical analysis of the stability of two types of intermediates(H2O)3M…N3^- and(H2O)3M…NCCH3 and the successful capture of two activated intermediates containing metal cadmium ions Cd2(μ3-N3)(μ3-OH)(μ5-CHDA)(1)and Cd(μ2-N3)(μ3-IBA)(2)(H2CHDA=1,3-cycloadipic acid and HIBA=4-(imidazol-1-yl)benzoic acid),which were achieved under the hydrothermal conditions and characterized by single-crystal XRD analysis.For the first time,the experimental and theoretical results reveal that the transition metal ions activate the azide rather than the cyano group of nitriles.In addition,the results of both the electrostatic potential basins analysis of activated intermediates(H2O)3M…N3^- and acetonitrile molecules obtained by the theoretical calculation and our recently reported experimental results reveal that the intermediates(H2O)3M…N3^- can be used as electrophilic reagent.Its uncoordinated terminal N atom can attack the N atom of the cyano group of acetonitrile to undergo a nucleophilic addition reaction during the chemical reaction progress,and then it may undergo a[2+3]cycloaddition reaction to in-situ form tetrazole.Moreover,with the aid of water molecules,its adducts may also occur similar to the Ritter-like reaction to in-situ form polynitrogen anion.Our findings may open a novel field of the in-situ synthesis of polynitrogen compounds based on the transition metal-catalyzed reactions of organonitrile and azide.