Three bis-formylfluorenimide ligands with different bridging groups were designed and synthesized, leading to the successful preparation of six novel alkylaluminum complexes through their reaction with alkylaluminum reagents (AlMe₃ or AlEt₃). Complexes 1 and 2 were obtained by the reaction of 1,2-propylene-bridged diamine (L¹) with AlMe₃ or AlEt₃. By reacting 1,2-cyclohexylene-bridged diamine (L²) with AlMe₃ or AlEt₃ to obtain complexes 3 and 4. The above ligands formed a bidentate four-coordinate structure with alkylaluminum, which involved the elimination of one alkyl group as the ligand reacted with alkylaluminum. The complexes 5 and 6 were synthesized through the reaction of 1,2-phenylene-bridged diamine (L³) with AlEt₃ in toluene or tetrahydrofuran. Notably, L³ exhibited unique reactivity compared with the other ligands, which formed a tridentate four-coordinated structure when reacting with alkylaluminum. The formation of the tridentate complex resulted from the introduction of a benzimidazole derivative or tetrahydrofuran (THF) molecule along with the elimination of two alkyl groups during its coordination with alkylaluminum. All complexes were characterized via ¹H NMR, ¹³C NMR, and elemental analysis, with structural determination confirmed through X-ray. Furthermore, the catalytic activity in the hydroboration reaction of aldehyde, ketone, and imines was investigated with these complexes as catalysts. Among them, complex 1 demonstrated excellent catalytic performance (up to 99% yield) and broad substrate compatibility (more than 30 substrates) at low catalyst loading (1 mol %) under mild reaction conditions.

中文翻译：

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烷基铝配合物，具有桥式双甲酰基芴酰亚胺配体，用于醛、酮和亚胺的氢硼化反应


设计合成了三种具有不同桥接基团的双甲酰基芴酰亚胺配体，通过与烷基铝试剂 （AlMe₃ 或 AlEt₃） 反应成功制备了 6 种新型烷基铝配合物。通过 1,2-丙烯桥二胺 （L¹） 与 AlMe₃ 或 AlEt₃ 反应获得复合物 1 和 2。通过将 1,2-环己基桥二胺 （L²） 与 AlMe₃ 或 AlEt₃ 反应得到络合物 3 和 4。上述配体与烷基铝形成双齿四配位结构，当配体与烷基铝反应时，这涉及消除一个烷基。配合物 5 和 6 是通过 1,2-苯基桥二胺 （L³） 与 AlEt₃ 在甲苯或四氢呋喃中反应合成的。值得注意的是，与其他配体相比，L³ 表现出独特的反应性，当与烷基铝反应时形成三齿四配位结构。三齿复合物的形成是由于苯并咪唑衍生物或四氢呋喃 （THF） 分子的引入以及在与烷基铝配位过程中两个烷基的消除。通过 ¹H NMR、¹³C NMR 和元素分析对所有复合物进行表征，并通过 X 射线确认结构测定。此外，以这些配合物为催化剂，研究了醛、酮和亚胺在硼氢化反应中的催化活性。 其中，复合物 1 在温和的反应条件下，在低催化剂负载量 （1 mol%） 下表现出优异的催化性能（高达 99% 的产率）和广泛的底物相容性（超过 30 种底物）。