Selective Oligomerization of Ethylene to Linear α-Olefins by Tetrahedral Cobalt(II) Complexes with 6-(Organyl)-2-(imino)pyridyl Ligands: Influence of the Heteroatom in the Organyl Group on the Catalytic Activity
摘要:
The oligomerization of ethylene to alpha-olefins has been obtained by MAO activation of tetrahedral Co-II complexes of iminopyridines substituted in the 6-position of the pyridine ring by thiophen-2-yl, furan-2-yl, or phenyl groups. An intriguing heteroatom effect has been noticed on both activity and selectivity, together with a change in the Co-II spin state upon activation of the dichloride precursors with MAO.
在通过MAO活化后,(亚氨基)吡啶钴(II)配合物CoCl 2 N 2催化一个降冰片烯(NB)分子与两个乙烯分子的链结,从而得到具有高活性和完全非对映选择性的外型-2,外型-3-乙基乙烯基降冰片烷。已获得高达270,000的周转频率[TOF,mol NB(mol Co×h)-1 ]。带有极性取代基(如降冰片烯甲醇和降冰片烯羧酸)的NB还可完成2E-1NB异三聚反应,条件是底物受三异丁基铝和对空间要求较低的复杂CoCl 2 N 2的保护。用作催化剂前体。在实验证据的基础上,提出了一种异三聚反应的机理。