SHOP-type nickel complexes with alkyl substituents on phosphorus, synthesis and catalyticethylene oligomerization
作者:Anthony Kermagoret、Pierre Braunstein
DOI:10.1039/b713451g
日期:——
The β-keto phosphorus ylides (n-Bu)3PCHC(O)Ph 6, (t-Bu)2PhPCHC(O)Ph 7, (t-Bu)Ph2PCHC(O)Ph 8, (n-Bu)2PhPCHC(O)Ph 9, (n-Bu)Ph2PCHC(O)Ph 10, Me2PhPCHC(O)Ph 11 and Ph3PCHC(O)(o-OMe-C6H4) 12 have been synthesized in 80–96% yields. The Ni(II) complexes [NiPhPh2PCHC(O)(o-OMeC6H4)}(PPh3)] 13, [NiPhPh(t-Bu)PCHC(O)Ph}(PPh3)] 15, [NiPh(n-Bu)2PCHC(O)Ph}(PPh3)] 16 and [NiPhPh(n-Bu)PCHC(O)Ph}(PPh3)] 17 have been prepared by reaction of equimolar amounts of [Ni(COD)2] and PPh3 with the β-keto phosphorus ylides 12 or 8–10, respectively, and characterized by 1H and 31P1H} NMR spectroscopy. NMR studies and the crystal structure determination of 13 indicated an interaction between the hydrogen atom of the C–H group α to phosphorus and the ether function. The complexes [NiPhPh2PCHC(O)Ph}(Py)] 18, [NiPhPh(t-Bu)PCHC(O)Ph}(Py)] 19, [NiPh(n-Bu)2PCHC(O)Ph}(Py)] 20, [NiPhPh(n-Bu)PCHC(O)Ph}(Py)] 21 and [NiPhMe2PCHC(O)Ph}(Py)] 22 have been isolated from the reactions of [Ni(COD)2] and an excess of pyridine with the β-keto phosphorus ylides Ph3PCHC(O)Ph 3 or 8–11, respectively, and characterized by 1H and 31P1H} NMR spectroscopy. Ligands 3, 8, 10 and 12 have been used to prepare in situ oligomerization catalysts by reaction with one equiv. of [Ni(COD)2] and PPh3 under an ethylene pressure of 30 or 60 bar. The catalyst prepared in situ from 12, [Ni(COD)2] and PPh3 was the most active of the series with a TON of 12 700 mol C2H4 (mol Ni)−1 under 30 bar ethylene. When the β-keto phosphorus ylide 8 was reacted in situ with three equiv. of [Ni(COD)2] and one equiv. of PPh3 under 30 bar of ethylene, ethylene polymerization was observed with a TON of 5500 mol C2H4 (mol Ni)−1.
(n-Bu)3PCHC(O)Ph 6,(t-Bu)2PhPCHC(O)Ph 7,(t-Bu)Ph2PCHC(O)Ph 8,(n-Bu)2PhPCHC(O)Ph 9、(n-Bu)Ph2PCHC(O)Ph 10、Me2PhPCHC(O)Ph 11 和 Ph3PCHC(O)(o-OMe-C6H4) 12 的合成,产率为 80-96%。[NiPhPh(n-Bu)2PCHC(O)Ph}(PPh3)] 16 和 [NiPhPh(n-Bu)PCHC(O)Ph}(PPh3)] 17 分别是通过等摩尔量的 [Ni(COD)2] 和 PPh3 与 β-酮磷酰化物 12 或 8-10 反应制备的,并通过 1H 和 31P1H} NMR 光谱进行了表征。核磁共振光谱进行表征。核磁共振研究和 13 的晶体结构测定表明,C-H 基团 α 至磷的氢原子与醚官能团之间存在相互作用。[NiPhPh(n-Bu)PCHC(O)Ph}(Py)] 21 和 [NiPhMe2PCHC(O)Ph}(Py)] 22 分别从 [Ni(COD)2] 和过量吡啶与 β-酮磷酰化物 Ph3PCHC(O)Ph 3 或 8-11 的反应中分离出来,并通过 1H 和 31P1H} NMR 光谱进行了表征。核磁共振光谱进行表征。配体 3、8、10 和 12 在 30 或 60 巴的乙烯压力下与 1 个等量的 [Ni(COD)2] 和 PPh3 反应,用于原位制备低聚催化剂。由 12、[Ni(COD)2] 和 PPh3 原位制备的催化剂是该系列中活性最高的催化剂,在 30 巴乙烯条件下,其吨位为 12 700 摩尔 C2H4(摩尔 Ni)-1。在 30 巴乙烯条件下,β-酮磷 Ylide 8 与 3 个等量的 [Ni(COD)2] 和 1 个等量的 PPh3 原位反应,观察到乙烯聚合,吨当量为 5500 摩尔 C2H4(摩尔 Ni)-1。