Cruz Tiago F C, López-Sánchez Belén, Lemos M Amélia N D A, Romerosa Antonio, Martins Luísa M D R S
Centro de Química Estrutural, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1000-049 Lisboa, Portugal.
Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, A-1060 Wien, Austria.
Dalton Trans. 2025 Aug 27. doi: 10.1039/d5dt01595b.
In this work, new copper(I) complexes of borane-functionalized bis(3,5-dimethylpyrazolyl)methane ligands were synthesized, characterized and used as catalysts for the cycloaddition of phenylacetylene and azides. Reaction of the allylated bis(3,5-dimethylpyrazolyl)methane proligand (La) with CuCl or [Cu(NCMe)]BF gave rise to the neutral copper chloride complex [(La)CuCl] (1a) or the binuclear cationic copper complex [(La)Cu(NCMe)]2(BF4)2 (2a2), respectively. The same reactions using a borane-functionalized bis(3,5-dimethylpyrazolyl)methane proligand (Lb) led to the isolation of complexes [(Lb)CuCl] (1b) and [(Lb)Cu(NCMe)2]BF4 (2b). The new complexes were characterized by NMR and FTIR spectroscopies, elemental analysis, cyclic voltammetry and, in selected cases, single-crystal X-ray diffraction. Complexes 1a, 1b, 2a2 and 2b catalyzed the cycloaddition of phenylacetylene and prepared benzyl azide to afford the respective 1,2,3-triazole products. When using complex 0.33 mol% of complex in the presence of 40 equivalents of diisopropylethylamine (DIPEA), a maximum yield of 97% with a maximum TOF value of 800 h was obtained. Complex 2b also catalyzed the cycloaddition of phenylacetylene with 7 azides prepared in 87%-99% yields. The borane-functionalized complexes 1b and 2b were, on average, 4-fold more active than their respective allylated analogues, and complex 2b readily led to the formation of the η-phenylacetylene complex [(Lb)Cu(η2-PhCCH)]BF4 (4) and the presumed detection of borane-centered Lewis pairs with MesN. These experimental observations, along with computational insights based on DFT calculations, indicated that the respective borane functionalities are beneficial to catalytic activity due to a substrate-directing effect.
在本工作中，合成、表征了硼烷官能化双（3,5 - 二甲基吡唑基）甲烷配体的新型铜（I）配合物，并将其用作苯乙炔与叠氮化物环加成反应的催化剂。烯丙基化双（3,5 - 二甲基吡唑基）甲烷前体配体（La）与CuCl或[Cu(NCMe)]BF反应，分别生成中性氯化铜配合物[(La)CuCl]（1a）或双核阳离子铜配合物[(La)Cu(NCMe)]2(BF4)2（2a2）。使用硼烷官能化双（3,5 - 二甲基吡唑基）甲烷前体配体（Lb）进行相同反应，得到配合物[(Lb)CuCl]（1b）和[(Lb)Cu(NCMe)2]BF4（2b）。通过核磁共振和傅里叶变换红外光谱、元素分析、循环伏安法以及在某些情况下的单晶X射线衍射对新配合物进行了表征。配合物1a、1b、2a2和2b催化苯乙炔与制备的苄基叠氮化物的环加成反应，得到相应的1,2,3 - 三唑产物。当在40当量的二异丙基乙胺（DIPEA）存在下使用0.33 mol%的配合物时，获得了97%的最大产率和800 h的最大TOF值。配合物2b还催化苯乙炔与制备的7种叠氮化物的环加成反应，产率为87% - 99%。硼烷官能化配合物1b和2b的活性平均比其各自的烯丙基化类似物高4倍，并且配合物2b容易生成η - 苯乙炔配合物[(Lb)Cu(η2 - PhCCH)]BF4（4），并推测检测到以硼烷为中心的与MesN的路易斯对。这些实验观察结果，连同基于密度泛函理论计算的计算见解，表明由于底物导向效应，相应的硼烷官能团对催化活性有益。
