Titanium Complexes Supported by an [OSSO]-Type Bis(phenolato) Ligand Based on a trans-Cyclooctanediyl Platform: Synthesis, Structures, and 1-Hexene Polymerization

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• 作者：Norio Nakata ; Tomoyuki Toda ; Tsukasa Matsuo ; Akihiko Ishii
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：January 2, 2012
• 年：2012
• 卷：51
• 期：1
• 页码：274-281
• 全文大小：512K
• 年卷期：v.51,no.1(January 2, 2012)
• ISSN：1520-510X

文摘

trans-Cyclooctanediyl-bridged [OSSO]-type ligand 4 reacts with TiCl₄(thf)₂ in toluene to produce the corresponding titanium(IV) dichloro complexes as an inseparable mixture of cis-伪 isomer 6a and cis-尾 isomer 6b in a ratio of 2:1, whereas treatment of dilithio salt of 4 with TiCl₃(thf)₃ in Et₂O afforded chloride-bridged dimeric titanium(III) complex 8, which indicated the antiferromagnetic character in a nonpolar solvent solution. Di(isopropoxy) titanium(IV) complex 10 having a C₂-symmetric cis-伪 configuration was synthesized by the reaction of 4 with Ti(OⁱPr)₄ in toluene as yellow crystals. Moreover, the reaction of 4 with Ti(NEt₂)₄ in toluene resulted in the unexpected formation of [OSSO]-type bis(phenolato)-bridged dinuclear diamido titanium(IV) complex 11, which adopted a distorted tetrahedral geometry on the titanium center. These titanium complexes were characterized on the basis of their NMR spectroscopic data, and the molecular structures of complexes 8, 10, and 11 were established by single crystal X-ray diffraction. The titanium(IV) and (III) complexes 6 and 8 upon activation with a cocatalyst in toluene polymerized 1-hexene isospecifically to produce poly(1-hexene) having high molecular weight (M_w = 22,000鈥?2,000 g mol^鈥?) and relatively narrow polydispersity (M_w/M_n = 1.7鈥?.8), albeit with low activity [0.27鈥?.0 g mmol(cat)^鈭? h^鈥?].