State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, PR China.
Chemistry. 2012 Feb 27;18(9):2674-84. doi: 10.1002/chem.201102682. Epub 2012 Jan 26.
A series of rare-earth-metal-hydrocarbyl complexes bearing N-type functionalized cyclopentadienyl (Cp) and fluorenyl (Flu) ligands were facilely synthesized. Treatment of [Y(CH(2)SiMe(3))(3)(thf)(2)] with equimolar amount of the electron-donating aminophenyl-Cp ligand C(5)Me(4)H-C(6)H(4)-o-NMe(2) afforded the corresponding binuclear monoalkyl complex [({C(5)Me(4)-C(6)H(4)-o-NMe(μ-CH(2))}Y{CH(2)SiMe(3)})(2)] (1a) via alkyl abstraction and C-H activation of the NMe(2) group. The lutetium bis(allyl) complex [(C(5)Me(4)-C(6)H(4)-o-NMe(2))Lu(η(3)-C(3)H(5))(2)] (2b), which contained an electron-donating aminophenyl-Cp ligand, was isolated from the sequential metathesis reactions of LuCl(3) with (C(5)Me(4)-C(6)H(4)-o-NMe(2))Li (1 equiv) and C(3)H(5)MgCl (2 equiv). Following a similar procedure, the yttrium- and scandium-bis(allyl) complexes, [(C(5)Me(4)-C(5)H(4)N)Ln(η(3)-C(3)H(5))(2)] (Ln=Y (3a), Sc (3b)), which also contained electron-withdrawing pyridyl-Cp ligands, were also obtained selectively. Deprotonation of the bulky pyridyl-Flu ligand (C(13)H(9)-C(5)H(4)N) by [Ln(CH(2)SiMe(3))(3)(thf)(2)] generated the rare-earth-metal-dialkyl complexes, [(η(3)-C(13)H(8)-C(5)H(4)N)Ln(CH(2)SiMe(3))(2)(thf)] (Ln=Y (4a), Sc (4b), Lu (4c)), in which an unusual asymmetric η(3)-allyl bonding mode of Flu moiety was observed. Switching to the bidentate yttrium-trisalkyl complex [Y(CH(2)C(6)H(4)-o-NMe(2))(3)], the same reaction conditions afforded the corresponding yttrium bis(aminobenzyl) complex [(η(3)-C(13)H(8)-C(5)H(4)N)Y(CH(2)C(6)H(4)-o-NMe(2))(2)] (5). Complexes 1-5 were fully characterized by (1)H and (13)C NMR and X-ray spectroscopy, and by elemental analysis. In the presence of both [Ph(3)C][B(C(6)F(5))(4)] and AliBu(3), the electron-donating aminophenyl-Cp-based complexes 1 and 2 did not show any activity towards styrene polymerization. In striking contrast, upon activation with [Ph(3)C][B(C(6)F(5))(4)] only, the electron-withdrawing pyridyl-Cp-based complexes 3, in particular scandium complex 3b, exhibited outstanding activitiy to give perfectly syndiotactic (rrrr >99%) polystyrene, whereas their bulky pyridyl-Flu analogues (4 and 5) in combination with [Ph(3)C][B(C(6)F(5))(4)] and AliBu(3) displayed much-lower activity to afford syndiotactic-enriched polystyrene.
一系列含有 N 型功能化环戊二烯基（Cp）和芴基（Flu）配体的稀土金属烃基配合物被简便地合成。用等摩尔量的给电子氨基苯基-Cp 配体 C5Me4H-C6H4-o-NMe2处理[Y(CH2SiMe3)3(thf)2]，得到相应的双核单烷基配合物[({C5Me4-C6H4-o-NMe(μ-CH2)}Y{CH2SiMe3})(2)]（1a），这是通过 NMe2基团的烷基取代和 C-H 活化实现的。含有给电子氨基苯基-Cp 配体的镥双（烯丙基）配合物[(C5Me4-C6H4-o-NMe2)Lu(η3-C3H5))(2)]（2b）是通过 LuCl3与（C5Me4-C6H4-o-NMe2)Li（1 当量）和 C3H5MgCl（2 当量）的复分解反应从分离得到的。按照类似的程序，也选择性地得到了含有吸电子吡啶-Cp 配体的钇和钪双（烯丙基）配合物[(C5Me4-C5H4N)Ln(η3-C3H5))(2)]（Ln=Y（3a），Sc（3b））。用[Ln(CH2SiMe3)3(thf)2]使体积庞大的吡啶-Flu 配体（C13H9-C5H4N）脱质子，生成了稀土金属二烷基配合物[(η3-C13H8-C5H4N)Ln(CH2SiMe3)2(thf)]（Ln=Y（4a），Sc（4b），Lu（4c）），其中观察到 Flu 部分的不寻常的不对称η3-烯丙基键合模式。用双齿的钇三烷基配合物[Y(CH2C6H4-o-NMe2)3]代替，相同的反应条件得到了相应的钇双（氨基苯甲基）配合物[(η3-C13H8-C5H4N)Y(CH2C6H4-o-NMe2)2]（5）。配合物 1-5 经（1）H 和（13）C NMR 以及 X 射线光谱分析，并经元素分析进行了充分表征。在[Ph3C][B(C6F5)4]和 AliBu3的存在下，给电子氨基苯基-Cp 基配合物 1 和 2 对苯乙烯聚合没有表现出任何活性。相比之下，仅用[Ph3C][B(C6F5)4]活化时，吸电子吡啶-Cp 基配合物 3，特别是钪配合物 3b，表现出出色的活性，得到完全间规（rrrr >99%）聚苯乙烯，而它们的体积庞大的吡啶-Flu 类似物（4 和 5）与[Ph3C][B(C6F5)4]和 AliBu3组合时，显示出较低的活性，得到间规富集聚苯乙烯。
