2-亚胺-1,10-邻二氮杂菲铁(Ⅱ)类催化剂活性与中心金属原子净电荷的关系

Relationship Between Catalytic Activity and Metal Atom Net Charge of Iron Complex Bearing 2-Imino-1,10-phenanthrolinyl Ligand

应用金属原子净电荷相关性(MANCC)方法研究了铁(Ⅱ)类催化剂活性.取代基的电子效应占主导作用的催化剂,活性与中心金属原子净电荷有较好的相关性.当取代基呈供电子效应时,催化剂活性随着电荷的增大而升高,当取代基呈吸电子效应时,催化剂活性随着电荷的增大而降低.在此基础上推测烯烃聚合反应催化过程中可能存在两种不同的活性中心,一种是[LFe—R]+,另一种是[LFe—R]2+或[Fe(Cl)RL]+.当取代基的电子效应和空间效应均对活性有影响时,发现催化剂的两卤素净电荷差值越小,催化活性越强.

The metal atom net charge correlation（MANCC） method was used to study catalytic activities of a series of asymmetric iron complexes bearing 2-imino-1,10-Phenanthroliyl ligands for ethylene oligomerization.If the catalytic activity is influenced mostly by electronic effect,it has a good correlation to the metal atom net charge.In general,catalytic activities of iron complexes bearing electron-donating alkyl groups increase with the net charges increasing.On the contrary,with the net charges increasing,catalytic activities decrease while the complexes contain electron-withdrawing halogen groups.Based on the above results,we speculated that two different activated centers probably existed in ethylene oligomerization which are [LFe-R＋and [LFe-R2＋（[Fe（Cl） RL＋）.When both the electronic and steric effects of coordinative ligand affect the catalytic activity,the charge difference on the two halogen atoms was correlated with it.And it is found that the cataly-tic activity is improved corresponding to the smaller charge difference.