Dinuclear Rare‐Earth Metal Alkyl Complexes Supported by Indolyl Ligands in μ‐η2:η1:η1 Hapticities and their High Catalytic Activity for Isoprene 1,4‐cis‐Polymerization |
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| Authors: | Guangchao Zhang Yun Wei Liping Guo Prof?Dr Xiancui Zhu Prof?Dr Shaowu Wang Prof?Dr Shuangliu Zhou Xiaolong Mu |
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| Institution: | 1. Laboratory of Functional Molecular Solids, Ministry of Education, Anhui Laboratory of Molecule‐Based Materials, School of Chemistry and Materials Science, Anhui Normal University, Wuhu, Anhui 241000 (P.?R. China), Fax: (+86)?553‐3883517;2. State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Shanghai 200032 (P.?R. China) |
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| Abstract: | Two series of new dinuclear rare‐earth metal alkyl complexes supported by indolyl ligands in novel μ‐η2:η1:η1 hapticities are synthesized and characterized. Treatment of RE(CH2SiMe3)3(thf)2] with 1 equivalent of 3‐(tBuN?CH)C8H5NH ( L1 ) in THF gives the dinuclear rare‐earth metal alkyl complexes trans‐(μ‐η2:η1:η1‐3‐{tBuNCH(CH2SiMe3)}Ind)RE(thf)(CH2SiMe3)]2 (Ind=indolyl, RE=Y, Dy, or Yb) in good yields. In the process, the indole unit of L1 is deprotonated by the metal alkyl species and the imino C?N group is transferred to the amido group by alkyl CH2SiMe3 insertion, affording a new dianionic ligand that bridges two metal alkyl units in μ‐η2:η1:η1 bonding modes, forming the dinuclear rare‐earth metal alkyl complexes. When L1 is reduced to 3‐(tBuNHCH2)C8H5NH ( L2 ), the reaction of Yb(CH2SiMe3)3(thf)2] with 1 equivalent of L2 in THF, interestingly, generated the trans‐(μ‐η2:η1:η1‐3‐{tBuNCH2}Ind)Yb(thf)(CH2SiMe3)]2 (major) and cis‐(μ‐η2:η1:η1‐3‐{tBuNCH2}Ind)Yb(thf)(CH2SiMe3)]2 (minor) complexes. The catalytic activities of these dinuclear rare‐earth metal alkyl complexes for isoprene polymerization were investigated; the yttrium and dysprosium complexes exhibited high catalytic activities and high regio‐ and stereoselectivities for isoprene 1,4‐cis‐polymerization. |
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| Keywords: | homogeneous catalysis isoprene ligand effects polymerization rare‐earth metals |
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