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Inne
Lithium diaminebis(aryloxido) complexes : synthesis, structures and reactivity in L-lactide polymerization.
Autorzy
Rok wydania
2015
Czasopismo
Numer woluminu
85
Strony
814-823
DOI
10.1016/j.poly.2014.10.006
Kolekcja
Język
Angielski
Typ publikacji
Artykuł
Lithium compounds of the tetradentate diaminebis(aryloxido) ligand [Li6(μ-L-κ4O,N,N,O)2(μ3-X)2(thf)4] (1, X = Br; 2, X = I) {L = [Me2NCH2CH2N(CH2-4-Me-C6H3O)2]2−} were synthesized in high yield using conventional deprotonation procedure as recently described for [Li6(μ-L-κ4O,N,N,O)2(μ3-Cl)2(thf)4] (3). The ligand precursor H2L was reacted with MeLi and LiX (X = Br, I) in thf to give related hexametallic species 1 and 2. Substitution of thf molecules in 1 by benzyl alcohol generates [Li6(μ-L-κ4O,N,N,O)2(μ-Br)2(BnOH)4] (4). A moisture causes partial hydrolization of 4 to form ionic species [Li4(μ-L-κ4O,N,N,O)(μ-LH-κ4O,N,N,O)(μ-H2O)2(BnOH)2]Br (5). Compounds 1, 2, 4 and 5 were characterized by chemical and physical techniques including X-ray crystallography for 1·thf, 4 and 5. The molecular structures of 1 and 4 contain the same Li6O4X2 core but they differ in the coordination mode of bromides, μ3-Br in 1 and μ-Br in 4. The cation of 5 adopts a ladder-like conformation, closed by the intramolecular hydrogen interactions. Preliminary experimental results show that 1–3 in the presence of benzyl alcohol efficiently initiate the ring-opening polymerization of l-lactide yielding isotactic polymers with relatively narrow polydispersity indexes.
Słowa kluczowe
Lithium complexes, Aminebis(aryloxido) ligands, Ring-opening polymerization, crystal structure, NMR spectra
Adres publiczny
http://dx.doi.org/10.1016/j.poly.2014.10.006
Strona internetowa wydawcy
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