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Synthesis and reactivity of dinucleating di(diamino)phenolate ligands for enforcing cooperativity Zhai, Xiaofang
Abstract
A new single-frame dinucleating di(diamino)phenolate ligand L has been synthesized and fully characterized, and its coordination chemistry with zinc precursors featuring ethyl, alkoxide, acetate and amide leaving groups has been investigated. Reaction of ligand L with diethyl zinc and Zn[N(SiMe₃)₂]₂ led to the formation of a trinulcear zinc complex 1 (L)Zn₃(CH₂CH₃)₄ and a dinuclear zinc amide complex 4 (L)Zn₂[N(SiMe₃)]₂, respectively. Deprotonation of ligand L followed by salt metathesis with Zn(OAc)₂ gave rise to a trinuclear zinc complex 3 [(L)Zn₃](μ-OAc)₄. The alkyl zinc complex 1 reacted with benzyl alcohol to afford a dinuclear alkoxy zinc complex 2. Complexes 1-3 were fully characterized by ¹H-NMR, ¹³C{¹H}-NMR, COSY, NOESY, HSQC and HMBC NMR spectroscopy and elemental analysis. The solid-state structures of Zn complexes 1-4 were characterized by single-crystal X-ray crystallography. The catalytic activities of complex 1 and 2 towards ring opening polymerization of racemic lactide (rac-lactide) have been studied. Complex 2 showed better control over molecular weight and dispersity than complex 1, and generated heterotactically inclined poly(lactic acid). However, complex 2 promoted extensive transesterification and depolymerization reaction. Complex 3 was found to be active to ROP of rac-lactide at high temperatures and it was active to CO₂/epoxide copolymerization.
Item Metadata
Title |
Synthesis and reactivity of dinucleating di(diamino)phenolate ligands for enforcing cooperativity
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2017
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Description |
A new single-frame dinucleating di(diamino)phenolate ligand L has been synthesized and fully characterized, and its coordination chemistry with zinc precursors featuring ethyl, alkoxide, acetate and amide leaving groups has been investigated. Reaction of ligand L with diethyl zinc and Zn[N(SiMe₃)₂]₂ led to the formation of a trinulcear zinc complex 1 (L)Zn₃(CH₂CH₃)₄ and a dinuclear zinc amide complex 4 (L)Zn₂[N(SiMe₃)]₂, respectively. Deprotonation of ligand L followed by salt metathesis with Zn(OAc)₂ gave rise to a trinuclear zinc complex 3 [(L)Zn₃](μ-OAc)₄. The alkyl zinc complex 1 reacted with benzyl alcohol to afford a dinuclear alkoxy zinc complex 2. Complexes 1-3 were fully characterized by ¹H-NMR, ¹³C{¹H}-NMR, COSY, NOESY, HSQC and HMBC NMR spectroscopy and elemental analysis. The solid-state structures of Zn complexes 1-4 were characterized by single-crystal X-ray crystallography.
The catalytic activities of complex 1 and 2 towards ring opening polymerization of racemic lactide (rac-lactide) have been studied. Complex 2 showed better control over molecular weight and dispersity than complex 1, and generated heterotactically inclined poly(lactic acid). However, complex 2 promoted extensive transesterification and depolymerization reaction. Complex 3 was found to be active to ROP of rac-lactide at high temperatures and it was active to CO₂/epoxide copolymerization.
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Genre | |
Type | |
Language |
eng
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Date Available |
2020-06-30
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0361982
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2018-02
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Campus | |
Scholarly Level |
Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Rights
Attribution-NonCommercial-NoDerivatives 4.0 International