氧化还原活性吡啶(二亚胺)(PDI)铁催化剂促进烯烃和二烯与环丁烷衍生物的可逆[2 + 2]环加成,其应用范围从燃料到化学可回收聚合物。金属环被确定为关键中间体,并计算了从单线态到三线态表面的自旋交叉,以促进负责形成四元环的还原偶联步骤。在这项工作中,研究了一系列空间和电子差异的 PDI 配体,用于乙烯和丁二烯与乙烯基环丁烷的 [2 + 2] 环加成。动力学研究表明,同样缺电子的支持配体观察到最快和最慢的周转,这些配体要么具有苯基取代的亚胺碳原子( Me BPDI),要么具有吡嗪核心( Me P Z DI)。虽然两种催化剂的氧化环化相对较慢,但还原偶联速率(由化学计量13 C 2 H 4标记研究确定)与周转频率相关。二态密度泛函理论研究和相关 ( iPr BPDI) 和 ( iPr P Z DI) 铁甲基配合物的不同电子结构揭示了由于配体 σ 供体 ( Me BPDI) 减少或金属 π 增强而导致的配体场强显着不同-背键合(
Heterogenized iron(II) complexes as highly active ethene polymerization catalysts
摘要:
The synthesis of new iron(Pi) diiminopyridine complexes and their heterogenization to give highly active ethene polymerization catalysts is described. The ligands are characterized by (HNMR)-H-1, (CNMR)-C-13 spectroscopy and GC/MS. The complexes are paramagnetic and were characterized by elemental analyses and mass spectrometry. The complexes were activated and heterogenized with a cocatalyst consisting of partially hydrolyzed trimethylaluminum (PHT) on silica gel and were used for ethene polymerization.The polymerization results and the polymer properties are presented. The influence of the catalyst structure, hydrogen and 1-hexene on the polymerization behavior is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.