Zr/Zr and Zr/Fe dinuclear complexes with flexible bridging ligands. preparation by olefin metathesis reaction of the mononuclear precursors and properties as polymerization catalysts
Zr/Zr and Zr/Fe dinuclear complexes with flexible bridging ligands. preparation by olefin metathesis reaction of the mononuclear precursors and properties as polymerization catalysts
复制标题
DOI：
10.1021/om0500321
复制
发表时间：
2005-04
期刊：
影响因子：
2.8
通讯作者：
J. Kuwabara;Daisuke Takeuchi;K. Osakada
中科院分区：
文献类型：
--
作者：
J. Kuwabara;Daisuke Takeuchi;K. Osakada
在钌配合物催化下，单锆配合物CpZrCl 2 {η 5 -C5 H4（CH 2）nCH =CH 2 }（n = 1，2，3）发生分子间乙烯基复分解反应，生成含桥联配体的双核配合物（CpZrCl 2）2 {μ-η 5，η 5 -C6 H4（CH 2）nCH =CH（CH 2）nC 5 H4}.产物在Pd/C催化下加氢得到具有柔性聚亚甲基链的络合物，该链桥接两个Cp 2 ZrCl 2基团。由单核锆配合物与烯丙基芴基配体的复分解反应，得到了一个桥联双芴基配体的双核配合物（CpZrCl 2）2（μ-η 5，η 5 -C13 H8 CH 2CH =CHCH 2C 13 H8）.（CpZrCl 2）2（μ-η 5，η 5 -C13 H8 CH 2CH =CHCH 2C 13 H8）的X射线晶体学研究表明，该化合物具有一个反式C =C双键，两个Zr中心位于桥连双芴基配体的不同侧. CpZrCl 2 {η 5 -C5 H4（CH 2）2 CH = CH 2}与丙烯酸二茂铁甲酯发生交叉复分解反应，生成了Zr/Fe双核配合物CpZrCl 2 {μ-η 5，η 5 -C5 H4（CH 2）2-CH=CHCOOCH 2 C5 H4}FeCp.双核配合物在甲基铝氧烷存在下催化乙烯和丙烯聚合。Zr/Zr双核配合物的催化乙烯聚合活性高于单核前体。桥联基团的长度和柔性也影响催化活性。
Mononuclear Zr complexes CpZrCl 2 {η 5 -C 5 H 4 (CH 2 ) n CH=CH 2 } (n = 1, 2, 3) undergo intermolecular metathesis of the vinyl group catalyzed by a Ru complex to produce dinuclear complexes with bridging ligands, (CpZrCl 2 ) 2 {μ-η 5 ,η 5 -C 6 H 4 (CH 2 ) n CH=CH(CH 2 ) n C 5 H 4 }. Hydrogenation of the products catalyzed by Pd/C affords complexes with a flexible polymethylene chain that bridges two Cp 2 ZrCl 2 groups. A dinuclear complex with a bridging bisfluorenyl ligand, (CpZrCl 2 ) 2 (μ-η 5 ,η 5 -C 1 3 H 8 CH 2 CH=CHCH 2 C 1 3 H 8 ), is also obtained from the metathesis of a mononuclear Zr complex with the allylfluorenyl ligand. X-ray crystallography of (CpZrCl 2 ) 2 (μ-η 5 ,η 5 -C 1 3 H 8 CH 2 CH=CHCH 2 C 1 3 H 8 ) revealed the molecular structure with a trans-C=C double bond and the two Zr centers situated at different sides of the bridging bisfluorenyl ligand. Cross metathesis reaction of CpZrCl 2 {η 5 -C5H4(CH2)2CH=CH2} and ferrocenylmethyl acrylate produces the Zr/Fe dinuclear complex CpZrCl 2 {μ-η 5 ,η 5 -C5H4(CH2)2-CH=CHCOOCH 2 C 5 H 4 }FeCp. The dinuclear complexes catalyze polymerization of ethylene and propylene in the presence of MAO (methylaluminoxane). The activity of the Zr/Zr dinuclear complexes for ethylene polymerization is higher than that of the mononuclear precursors. The length and flexibility of the bridging group of the biscyclopentadienyl ligand also influence the catalytic activity.