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首页> 外文期刊>Chemistry: A European journal >Borane and borohydride complexes of the rare-earth elements: Synthesis, structures, and butadiene polymerization catalysis
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Borane and borohydride complexes of the rare-earth elements: Synthesis, structures, and butadiene polymerization catalysis

机译：稀土元素的硼烷和硼氢化物配合物：合成，结构和丁二烯聚合催化

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摘要

The reaction of potassium 2,5-bis[N-(2,6-diisopropylphenyl)iminomethyl] pyrrolyl [(dip_2-pyr)K] with the borohydrides of the larger rare-earth metals, [Ln(BH_4)_3(thf)_3] (Ln = La, Nd), afforded the expected products [Ln(BH_4)_2(dip _2-pyr)(thf)_2]. As usual, the trisborohydrides reacted like pseudohalide compounds forming KBH_4 as a by-product. To compare the reactivity with the analogous halides, the dimeric neodymium complex [NdCl _2(dip_2-pyr)(thf)]_2 was prepared by reaction of [(dip_2-pyr)K] with anhydrous NdCl_3. Reaction of [(dip _2-pyr)K] with the borohydrides of the smaller rare-earth metals, [Sc(BH_4)_3(thf)_2] and [Lu(BH_4) _3(thf)_3], resulted in a redox reaction of the BH _4~- group with one of the Schiff base functions of the ligand. In the re-suiting products, [Ln(BH_4){(dip)(dipBH _3)-pyr}(thf)_2] (Ln = Sc, Lu), a dinegatively charged ligand with a new amido function, a Schiff base, and the pyrrolyl function is bound to the metal atom. The by-product of the reaction of the BH _4~- anion with the Schiff base function (a BH_3 molecule) is trapped in a unique reaction mode in the coordination sphere of the metal complex. The BH_3 molecule coordinates in an if fashion to the metal atom. The rareearth-metal atoms are surrounded by the η~2- coordinated BH_3 molecule, the η~3-coordinated BH _4- anion, two THF molecules, and the nitrogen atoms from the Schiff base and the pyrrolyl function. All new compounds were characterized by single-crystal X-ray diffraction. Low-temperature X-ray diffraction data at 6 K were collected to locate the hydrogen atoms of [Lu(BH_4){(dip)(dip- BH_3)-pyr}(thf)_2]. The (DIP_2-pyr)- borohydride and chloride complexes of neodymium, [Nd(BH_4) _2- (dip_2-pyr)(thf)_2] and [NdCl _2(dip_2-pyr)(thf)]_2, were also used as Ziegler-Natta catalysts for the polymerization of 1,3butadiene to yield poly(cis-l,4-butadiene). Very high activities and good cis selectivities were observed by using each of these complexes as a catalyst in the presence of various cocatalyst mixtures.
机译：2,5-双[N-（2,6-二异丙基苯基）亚氨基甲基]吡咯钾[（dip_2-pyr）K]与较大稀土金属[Ln（BH_4）_3（thf）的硼氢化物的反应_3]（Ln = La，Nd），得到了预期的产物[Ln（BH_4）_2（dip _2-pyr）（thf）_2]。通常，三硼氢化物像假卤化物一样反应，形成KBH_4作为副产物。为了比较与类似卤化物的反应性，通过[[dip_2-pyr）K]与无水NdCl_3的反应制备了二聚钕络合物[NdCl _2（dip_2-pyr）（thf）] _ 2。 [（dip _2-pyr）K]与较小的稀土金属[Sc（BH_4）_3（thf）_2]和[Lu（BH_4）_3（thf）_3]的硼氢化物反应，导致氧化还原BH _4〜-基团与配体的席夫碱功能之一的反应。在重新装配的产品中，[Ln（BH_4）{（dip）（dipBH _3）-pyr}（thf）_2]（Ln = Sc，Lu），带负电荷的配体，具有新的酰胺功能，席夫碱，吡咯基官能团键合到金属原子上。 BH _ 4-阴离子与席夫碱功能（BH _ 3分子）反应的副产物以独特的反应方式被捕集在金属络合物的配位域中。 BH_3分子以if方式与金属原子配位。稀土金属原子被η〜2-配位的BH_3分子，η〜3-配位的BH _4-阴离子，两个THF分子以及席夫碱和吡咯基官能团中的氮原子包围。所有新化合物均通过单晶X射线衍射表征。收集6 K的低温X射线衍射数据以定位[Lu（BH_4）{（dip）（dip-BH_3）-pyr}（thf）_2]的氢原子。钕的[DIP_2-pyr）-硼氢化物和氯化物络合物[Nd（BH_4）_2-（dip_2-pyr）（thf）_2]和[NdCl _2（dip_2-pyr）（thf）] _ 2也用作Ziegler-Natta催化剂，用于1,3丁二烯的聚合反应，生成聚（顺式1,4,4-丁二烯）。在各种助催化剂混合物的存在下，通过将这些配合物用作催化剂，观察到非常高的活性和良好的顺式选择性。

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