Noonikara-Poyil Anurag, Muñoz-Castro Alvaro, Dias H V Rasika
Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX 76019, USA.
Grupo de Química Inorgánica y Materiales Moleculares, Facultad de Ingenieria, Universidad Autonoma de Chile, El Llano Subercaseaux 2801, Santiago 8910060, Chile.
Molecules. 2021 Dec 21;27(1):16. doi: 10.3390/molecules27010016.
Copper plays an important role in alkyne coordination chemistry and transformations. This report describes the isolation and full characterization of a thermally stable, copper(I) acetylene complex using a highly fluorinated bis(pyrazolyl)borate ligand support. Details of the related copper(I) complex of HC≡CSiMe are also reported. They are three-coordinate copper complexes featuring η-bound alkynes. Raman data show significant red-shifts in C≡C stretch of [HB(3,5-(CF)Pz)]Cu(HC≡CH) and [HB(3,5-(CF)Pz)]Cu(HC≡CSiMe) relative to those of the corresponding alkynes. Computational analysis using DFT indicates that the Cu(I) alkyne interaction in these molecules is primarily of the electrostatic character. The π-backbonding is the larger component of the orbital contribution to the interaction. The dinuclear complexes such as Cu(μ-[3,5-(CF)Pz])(HC≡CH) display similar Cu-alkyne bonding features. The mononuclear [HB(3,5-(CF)Pz)]Cu(NCMe) complex catalyzes [3 + 2] cycloadditions between tolyl azide and a variety of alkynes including acetylene. It is comparatively less effective than the related trinuclear copper catalyst {μ-[3,5-(CF)Pz]Cu} involving bridging pyrazolates.
铜在炔烃配位化学及转化过程中发挥着重要作用。本报告描述了一种使用高度氟化的双（吡唑基）硼酸酯配体载体分离并全面表征热稳定的铜（I）乙炔配合物的过程。同时也报道了HC≡CSiMe相关铜（I）配合物的细节。它们是具有η配位炔烃的三配位铜配合物。拉曼数据表明，相对于相应炔烃，[HB(3,5-(CF)Pz)]Cu(HC≡CH)和[HB(3,5-(CF)Pz)]Cu(HC≡CSiMe)中C≡C伸缩振动有显著红移。使用密度泛函理论（DFT）的计算分析表明，这些分子中Cu（I）与炔烃的相互作用主要是静电性质。π反馈键是轨道对相互作用贡献的较大组成部分。双核配合物如Cu(μ-[3,5-(CF)Pz])(HC≡CH)表现出类似的Cu-炔烃键合特征。单核[HB(3,5-(CF)Pz)]Cu(NCMe)配合物催化甲苯叠氮化物与包括乙炔在内的多种炔烃之间的[3 + 2]环加成反应。它的催化效果相对低于涉及桥连吡唑盐的相关三核铜催化剂{μ-[3,5-(CF)Pz]Cu}。
