2,5-Bis{N-(2,6-diisopropylphenyl)iminomethyl}pyrrolyl borohydride complexes of the divalent lanthanides - Synthesis, structures and ring-opening polymerization of ¦Å-caprolactone

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• 作者：Matthias Schmid ; Sophie M. Guillaume ; Peter W. Roesky
• 关键词：Borohydrides ; Caprolactone ; Lanthanide ; N Ligands ; Polyester ; Ring-opening polymerization (ROP)
• 刊名：Journal of Organometallic Chemistry
• 出版年：2013
• 出版时间：1 November, 2013
• 年：2013
• 卷：744
• 期：Complete
• 页码：68-73
• 全文大小：663 K

文摘

The borohydride complexes [(DIP₂pyr)Ln(BH₄)(THF)₃] (Ln?=?Eu (1), Yb (2); (DIP₂pyr)^??=?2,5-bis{N-(2,6-diisopropylphenyl)iminomethyl}pyrrolyl) were synthesized by reaction of [Ln(BH₄)₂(THF)₂] (Ln?=?Eu, Yb) with [(DIP₂pyr)K] in THF. The X-ray solid-state structures of 1 and 2 show that the (DIP₂pyr)^? ligand coordinates in a ¦Ê³-fashion to the europium atom, while the smaller ytterbium atom is only ¦Ê²-coordinated by the (DIP₂pyr)^? ligand with one Schiff base nitrogen atom pointing away from the metal center. Whereas compound 1 can be stored under nitrogen at room temperature for several months, compound 2 is less stable, decomposing under these same conditions. The corresponding two-fold ligated compound [(DIP₂pyr)₂Yb(THF)] was isolated from the reaction of [(DIP₂pyr)K] with anhydrous ytterbium diiodide in THF. The X-ray solid state structure suggests one ¦Ê³-coordinated (DIP₂pyr)^? ligand while the second ligand is ¦Ê²-coordinated to the metal center. Compound 1 was found active in promoting the ring-opening polymerization (ROP) of ¦Å-caprolactone under mild conditions.