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Alhashmialameer D, Ikpo N, Collins J, et al. Ring-opening polymerization of rac-lactide mediated by tetrametallic lithium and sodium diamino-bis(phenolate) complexes. Dalton Trans. 2015;44(46):20216-31doi: 10.1039/c5dt03119b.
Alhashmialameer, D., Ikpo, N., Collins, J., Dawe, L. N., Hattenhauer, K., & Kerton, F. M. (2015). Ring-opening polymerization of rac-lactide mediated by tetrametallic lithium and sodium diamino-bis(phenolate) complexes. Dalton transactions (Cambridge, England : 2003), 44(46), 20216-31. https://doi.org/10.1039/c5dt03119b
Alhashmialameer, Dalal, et al. "Ring-opening polymerization of rac-lactide mediated by tetrametallic lithium and sodium diamino-bis(phenolate) complexes." Dalton transactions (Cambridge, England : 2003) vol. 44,46 (2015): 20216-31. doi: https://doi.org/10.1039/c5dt03119b
Alhashmialameer D, Ikpo N, Collins J, Dawe LN, Hattenhauer K, Kerton FM. Ring-opening polymerization of rac-lactide mediated by tetrametallic lithium and sodium diamino-bis(phenolate) complexes. Dalton Trans. 2015 Dec 14;44(46):20216-31. doi: 10.1039/c5dt03119b. PMID: 26538475.
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Dalton Trans. 2015 Dec 14;44(46):20216-31. doi: 10.1039/c5dt03119b.

Ring-opening polymerization of rac-lactide mediated by tetrametallic lithium and sodium diamino-bis(phenolate) complexes.

Dalton transactions (Cambridge, England : 2003)

Dalal Alhashmialameer, Nduka Ikpo, Julie Collins, Louise N Dawe, Karen Hattenhauer, Francesca M Kerton

Affiliations

  1. Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland, Canada A1B 3X7. [email protected].
  2. C-CART X-ray Diffraction Laboratory, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.
  3. Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland, Canada A1B 3X7. [email protected] and C-CART X-ray Diffraction Laboratory, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.

PMID: 26538475 DOI: 10.1039/c5dt03119b

Abstract

Lithium and sodium compounds supported by tetradentate amino-bis(phenolato) ligands, [Li2(N2O2(BuBuPip))] (1), [Na2(N2O2(BuBuPip))] (2) (where [N2O2(BuBuPip)] = 2,2'-N,N'-homopiperazinyl-bis(2-methylene-4,6-tert-butylphenol), and [Li2(N2O2(BuMePip))] (3), [Na2(N2O2(BuMePip))] (4) (where [N2O2(BuMePip)] = 2,2'-N,N'-homopiperazinyl-bis(2-methylene-4-methyl-6-tert-butylphenol) were synthesized and characterized by NMR spectroscopy and MALDI-TOF mass spectrometry. Variable temperature NMR experiments were performed to understand solution-phase dynamics. The solid-state structures of 1 and 4 were determined by X-ray diffraction and reveal tetrametallic species. PGSE NMR spectroscopic data suggests that 1 maintains its aggregated structure in CD2Cl2. The complexes exhibit good activity for controlled ring-opening polymerization of rac-lactide (LA) both solvent free and in solution to yield PLA with low dispersities. Stoichiometric reactions suggest that the formation of PLA may proceed by the typical coordination-insertion mechanism. For example, (7)Li NMR experiments show growth of a new resonance when 1 is mixed with 1 equiv. LA and (1)H NMR data suggests formation of a Li-alkoxide species upon reaction of 1 with BnOH.

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