Formation and structural properties of salicylaldiminato complexes of zirconium and titanium
Formation and structural properties of salicylaldiminato complexes of zirconium and titanium
复制标题
锆钛水杨醛亚胺络合物的形成及结构性质
DOI：
10.1016/s0020-1693(99)00573-3
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发表时间：
2000
影响因子：
2.8
通讯作者：
P. Saarenketo
中科院分区：
文献类型：
--
作者：
Joachim W. Strauch;T. H. Warren;G. Erker;R. Fröhlich;P. Saarenketo
茂金属阳离子[Cp 2 ZrCH 3（THF）+]（2，带有BPh 4 −阴离子）与N-异丙基水杨醛亚胺（1a）反应，释放出甲烷并形成假四面体[（κO，κN-salicylaldiminato）ZrCp 2 +]配合物3，其结构经X射线衍射表征。通过用正丁基锂处理的1a的去质子化产生相应的锂化试剂4a，其在晶体中表现出四聚体结构，具有立方Li 4 O 4核心结构。用Zr（NMe 2）2Cl 2（dme）（5）处理4a得到八面体双（N-异丙基水杨醛亚胺）Zr（NMe 2）2配合物7a。X-射线晶体结构分析表明，配体7a中的醛亚胺氧原子在中心金属原子上相互反式排列。用试剂Zr（NMe 2）4（6）处理N-异丙基、N-环己基和N-（2，6-二异丙基苯基）水杨酰亚胺（1a，B，d）直接导致以良好产率形成相应的八面体（lig）2 Zr（NMe 2）2配合物7a，7 B b和7 d（也通过X射线衍射表征）。用Me 3Si-Cl处理7 b和7 d，用氯化物取代的NMe 2取代基，分别得到相应的lig 2 ZrCl 2配合物8b和8d。X-射线晶体结构分析表明，8d与κO，κ N-螯合配体的醛亚胺氮原子形成八面体配位，在锆上反式取向。配合物8b经历对映体化过程，随后进行动态NMR光谱（ΔG NMR. (268 K）约12 kcal mol−1）。四氯化钛与1d形成中性1：2加合物。所得的双甜菜碱型加合物9d的NMR分析和X射线晶体结构分析揭示了含有两个反式-Ti：O（芳基）键的八面体钛络合物的形成。酚氢原子转移到醛亚胺氮形成分子内亚胺盐。通过用NEt 3处理从9d中除去两当量的HCl，得到双[N-（2，6-二异丙基苯基）水杨醛亚胺] TiCl 2络合物10 d（通过X射线衍射表征）。在一锅法中，TiCl 4与N-苯基水杨醛亚胺（1c）和三乙胺以1：2：2的比例反应，直接得到相应的（κO，κN-lig）2 TiCl 2配合物10 c。10 c的X射线晶体结构分析揭示了配体氧原子的反式取向，就像加合物中间体9中一样。在用甲基铝氧烷活化时，络合物8d、10 c和10 d形成用于乙烯聚合的催化剂。
The metallocene cation [Cp2ZrCH3(THF)+] (2, with BPh4−anion) reacts with N-isopropylsalicylaldimine (1a) by liberation of methane and formation of the pseudotetrahedral [(κO,κN-salicylaldiminato)ZrCp2+] complex 3 that was characterized by X-ray diffraction. Deprotonation of 1a by treatment with n-butyllithium yields the corresponding lithiated reagent 4a, that exhibits a tetrameric structure in the crystal, featuring a cubic Li4O4core structure. Treatment of 4a with Zr(NMe2)2Cl2(dme) (5) yields the octahedral bis(N-isopropylsalicylaldiminato)Zr(NMe2)2complex 7a. The X-ray crystal structure analysis of 7a has revealed that the aldiminato oxygen atoms of the κO,κN-chelate ligand are oriented trans to each other at the central metal atom. Treatment of the N-isopropyl, the N-cyclohexyl- and the N-(2,6-diisopropylphenyl)salicylimines (1a,b,d) with the reagent Zr(NMe2)4(6) directly results in the formation of the respective octahedral (lig)2Zr(NMe2)2complexes 7a, 7b (also characterized by X-ray diffraction), and 7d in good yields. Treatment of 7b and 7d with Me3Si-Cl replaced the NMe2substituents by chloride to yield the corresponding lig2ZrCl2complexes 8b and 8d, respectively. The X-ray crystal structure analysis of 8d showed an octahedral coordination with the aldiminato nitrogen atoms of the κO,κN-chelate ligands now being trans-oriented at zirconium. Complex 8b undergoes an enantiomerization process that is followed by dynamic NMR spectroscopy (ΔG≠enant.(268 K)≈12 kcal mol−1). Titanium tetrachloride forms a neutral 1:2 adduct with 1d. The NMR analysis and X-ray crystal structure analysis of the resulting bisbetaine-type adduct 9d reveals the formation of an octahedral titanium complex that contains two trans-TiO(aryl) bonds. The phenolic hydrogen atoms were transferred to the aldimine nitrogens to form an intramolecular iminium salt. Two equivalents of HCl are removed from 9d by treatment with NEt3to yield the bis[N-(2,6-diisopropylphenyl)salicylaldiminato]TiCl2complex 10d (characterized by X-ray diffraction). In a one-pot procedure TiCl4reacts with N-phenylsalicylaldimine (1c) and triethylamine in a 1:2:2 ratio to directly yield the corresponding (κO,κN-lig)2TiCl2complex 10c. The X-ray crystal structure analysis of 10c reveals a trans-orientation of ligand oxygen atoms, just like in the adduct intermediate 9. Upon activation with methylalumoxane the complexes 8d, 10c, and 10d form catalysts for the polymerization of ethene.