Bifunctional yttrium(III) and titanium(IV) NHC catalysts for lactide polymerisation.
نویسندگان
چکیده
Lewis acidic yttrium(III) and titanium(IV) derivatives of anionic, metal-tethered carbenes apparently act as bifunctional catalysts for the polymerisation of D,L-lactide, using a combination of Lewis acid and base functionalities to initiate ring opening of the cyclic monomer; the alcohol- and amino-functionalised carbenes from which they derive provide models for the first insertion step, and also display metal-free polymerisation catalysis to generate polylactic acid.
منابع مشابه
Computational Studies on the Selective Polymerization of Lactide Catalyzed by Bifunctional Yttrium NHC Catalyst
A theoretical investigation of the ring-opening polymerization (ROP) mechanism of rac-lactide (LA) with an yttrium complex featuring a N-heterocyclic carbine (NHC) tethered moiety is reported. It was found that the carbonyl of lactide is attacked by N(SiMe3)2 group rather than NHC species at the chain initiation step. The polymerization selectivity was further investigated via two consecutive i...
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متن کاملNovel Ti(IV) and Zr(IV) complexes and their application in the ring-opening polymerisation of cyclic esters.
A series of group 4 amine tris(phenolate) complexes have been prepared and characterised by single crystal X-ray diffraction and multinuclear NMR spectroscopy. It was found that the ligands afforded monomeric titanium complexes and dimeric zirconium structures in the solid-state. The complexes have been tested for the ring-opening polymerisation of rac-lactide under both solution and melt condi...
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ورودعنوان ژورنال:
- Chemical communications
دوره 10 شماره
صفحات -
تاریخ انتشار 2006