College of Pharmacy, Key Laboratory of Pharmaceutical Quality Control of Hebei Province, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, Hebei University, Baoding 071002, Hebei, P. R. China.
Inorg Chem. 2022 Sep 19;61(37):14662-14672. doi: 10.1021/acs.inorgchem.2c02027. Epub 2022 Sep 5.
The metal-catalyzed hydrogenolysis of polymers is important in waste recycling; however, it is limited by the harsh reaction conditions and the low activities of catalysts, especially for earth-abundant metal-based catalysts. Herein, we perform a comprehensive study on the hydrogenolysis of polyurethane model catalyzed by Fe-, Mn-, Ru-, and Ir-MACHO pincer complexes and propose a cascade mechanism comprising two-level hydrogenolysis and the hydrogenation of formaldehyde. In addition, the substrates and ligands are modulated to improve the activities of chemical recycling to monomer. It is found that the pincer ligands could dissociate from the metal centers at high reaction temperatures and further result in the deactivation of catalysts. The rigid Fe and Mn catalysts with tetradentate cyclic ligands are designed following the guidance, and the computations suggest that those designed catalysts could have high stabilities and activities.
金属催化的聚合物氢解在废物回收中很重要；然而，它受到苛刻的反应条件和催化剂活性低的限制，特别是对于丰富的金属基催化剂。在此，我们对 Fe、Mn、Ru 和 Ir-MACHO 夹钳配合物催化的聚氨酯模型的氢解进行了全面研究，并提出了包括两级氢解和甲醛加氢的级联机制。此外，还对底物和配体进行了调节，以提高单体化学回收的活性。研究发现，在较高的反应温度下，夹钳配体可以从金属中心解离，从而导致催化剂失活。受此启发，设计了具有四齿环状配体的刚性 Fe 和 Mn 催化剂，计算表明，这些设计的催化剂可能具有较高的稳定性和活性。
