Department of Chemistry, University of California, Riverside, California 92521, United States.
J Am Chem Soc. 2023 Mar 8;145(9):4964-4968. doi: 10.1021/jacs.2c13610. Epub 2023 Feb 24.
Sulfated aluminum oxide (), a high surface area material containing sulfate anions that behave like weakly coordinating anions, reacts with Ta(═CHBu)(CHBu) to form [Ta(CHBu)(O-)][] (). Subsequent treatment with H forms Ta-H sites supported on that are active in hydrogenolysis and alkane metathesis reactions. In both reactions Ta-H is more active than related neutral Ta-H sites supported on silica. This reaction chemistry extends to melts of high-density polyethylene (HDPE), where Ta-H converts 30% of a low molecular weight HDPE ( = 2.5 kg mol; = 3.6) to low molecular weight paraffins under hydrogenolysis conditions. Under alkane metathesis conditions Ta-H converts this HDPE to a high MW fraction ( = 6.2 kDa; = 2.3) and low molecular weight alkane products (C-C). These results show that incorporating charge as a design element in supported d metal hydrides is a viable strategy to increase the reaction rate in challenging reactions involving reorganization of C-C bonds in alkanes.
硫酸化氧化铝（）是一种高表面积的材料，其表面含有硫酸根阴离子，这些阴离子表现出类似于弱配位阴离子的性质。它与 Ta(═CHBu)(CHBu) 反应，形成 Ta(CHBu)(O-)。随后用 H 处理，形成负载在 上的 Ta-H 位，这些位在氢解和烷烃复分解反应中具有活性。在这两种反应中，Ta-H 比负载在硅胶上的相关中性 Ta-H 位具有更高的活性。这种反应化学延伸到高密度聚乙烯（HDPE）的熔体中，在氢解条件下，Ta-H 将低分子量 HDPE（= 2.5 kg mol；= 3.6）的 30%转化为低分子量的石蜡。在烷烃复分解条件下，Ta-H 将这种 HDPE 转化为高分子量部分（= 6.2 kDa；= 2.3）和低分子量烷烃产物（C-C）。这些结果表明，在负载 d 金属氢化物中引入电荷作为设计元素是一种可行的策略，可以提高涉及烷烃中 C-C 键重排的挑战性反应的反应速率。
