Synthesis and structures of calcium and strontium 2,4-di-tert-butylphenolates and their reactivity towards the amine co-initiated ring-opening polymerisation of rac-lactide.
Calcium and strontium metals react with Hg(C6F5)2 and 2,4-di-tert-butylphenol (H-DBP) in tetrahydrofuran (THF) and 1,2-dimethoxyethane (DME) to give [Ca(DBP)2(THF)4] (1), [Ca2(DBP)4(DME)4(μ-DME)] (2), [Sr3(μ-DBP)6(THF)6] (3), and [Sr2(DBP)(μ-DBP)3(DME)3] (4). Compound 1 is a six coordinate trans-oct...
| Main Authors: | , , , , , , |
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| Format: | Journal article |
| Language: | English |
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2013
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| _version_ | 1826270635082383360 |
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| author | Clark, L Deacon, G Forsyth, C Junk, P Mountford, P Townley, J Wang, J |
| author_facet | Clark, L Deacon, G Forsyth, C Junk, P Mountford, P Townley, J Wang, J |
| author_sort | Clark, L |
| collection | OXFORD |
| description | Calcium and strontium metals react with Hg(C6F5)2 and 2,4-di-tert-butylphenol (H-DBP) in tetrahydrofuran (THF) and 1,2-dimethoxyethane (DME) to give [Ca(DBP)2(THF)4] (1), [Ca2(DBP)4(DME)4(μ-DME)] (2), [Sr3(μ-DBP)6(THF)6] (3), and [Sr2(DBP)(μ-DBP)3(DME)3] (4). Compound 1 is a six coordinate trans-octahedral monomer, whereas in binuclear 2 two seven-coordinate Ca centres are bridged by a DME ligand. In 3 a central Sr is connected by three bridging DBP groups to each of two terminal Sr(THF)3 moieties, all metal atoms being six coordinate. Compound 4 has one six- and one seven-coordinate Sr, bridged by three DBP ligands, the former Sr also having a terminal DBP and a bidentate DME ligand and the latter two DME ligands. Complexes 2 and 4 act as ring-opening polymerisation (ROP) catalysts for the benzyl alcohol or benzylamine co-initiated ROP rac-lactide forming atactic alcohol- or amine-terminated polylactide H-[PLA]-XBn (X = O or NH) with reasonable control of molecular weight via an activated monomer propagation mechanism. Kinetic studies for BnNH2 found the unusual rate expression -d[LA]/dt = k(p(Ae))[2 or 4]0[rac-LA](2)[BnNH2]0(2.5) (k(p(Ca)) ≈ 1.7 ×k(p(Sr))). Preliminary studies suggest that [Y(DBP)3(THF)2] also catalyses amine or alcohol co-initiated ROP by an activated monomer mechanism without loss of a phenoxide ligand. |
| first_indexed | 2024-03-06T21:43:57Z |
| format | Journal article |
| id | oxford-uuid:48e683b3-f4a5-4087-a816-d386856b5f5c |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T21:43:57Z |
| publishDate | 2013 |
| record_format | dspace |
| spelling | oxford-uuid:48e683b3-f4a5-4087-a816-d386856b5f5c2022-03-26T15:28:26ZSynthesis and structures of calcium and strontium 2,4-di-tert-butylphenolates and their reactivity towards the amine co-initiated ring-opening polymerisation of rac-lactide.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:48e683b3-f4a5-4087-a816-d386856b5f5cEnglishSymplectic Elements at Oxford2013Clark, LDeacon, GForsyth, CJunk, PMountford, PTownley, JWang, JCalcium and strontium metals react with Hg(C6F5)2 and 2,4-di-tert-butylphenol (H-DBP) in tetrahydrofuran (THF) and 1,2-dimethoxyethane (DME) to give [Ca(DBP)2(THF)4] (1), [Ca2(DBP)4(DME)4(μ-DME)] (2), [Sr3(μ-DBP)6(THF)6] (3), and [Sr2(DBP)(μ-DBP)3(DME)3] (4). Compound 1 is a six coordinate trans-octahedral monomer, whereas in binuclear 2 two seven-coordinate Ca centres are bridged by a DME ligand. In 3 a central Sr is connected by three bridging DBP groups to each of two terminal Sr(THF)3 moieties, all metal atoms being six coordinate. Compound 4 has one six- and one seven-coordinate Sr, bridged by three DBP ligands, the former Sr also having a terminal DBP and a bidentate DME ligand and the latter two DME ligands. Complexes 2 and 4 act as ring-opening polymerisation (ROP) catalysts for the benzyl alcohol or benzylamine co-initiated ROP rac-lactide forming atactic alcohol- or amine-terminated polylactide H-[PLA]-XBn (X = O or NH) with reasonable control of molecular weight via an activated monomer propagation mechanism. Kinetic studies for BnNH2 found the unusual rate expression -d[LA]/dt = k(p(Ae))[2 or 4]0[rac-LA](2)[BnNH2]0(2.5) (k(p(Ca)) ≈ 1.7 ×k(p(Sr))). Preliminary studies suggest that [Y(DBP)3(THF)2] also catalyses amine or alcohol co-initiated ROP by an activated monomer mechanism without loss of a phenoxide ligand. |
| spellingShingle | Clark, L Deacon, G Forsyth, C Junk, P Mountford, P Townley, J Wang, J Synthesis and structures of calcium and strontium 2,4-di-tert-butylphenolates and their reactivity towards the amine co-initiated ring-opening polymerisation of rac-lactide. |
| title | Synthesis and structures of calcium and strontium 2,4-di-tert-butylphenolates and their reactivity towards the amine co-initiated ring-opening polymerisation of rac-lactide. |
| title_full | Synthesis and structures of calcium and strontium 2,4-di-tert-butylphenolates and their reactivity towards the amine co-initiated ring-opening polymerisation of rac-lactide. |
| title_fullStr | Synthesis and structures of calcium and strontium 2,4-di-tert-butylphenolates and their reactivity towards the amine co-initiated ring-opening polymerisation of rac-lactide. |
| title_full_unstemmed | Synthesis and structures of calcium and strontium 2,4-di-tert-butylphenolates and their reactivity towards the amine co-initiated ring-opening polymerisation of rac-lactide. |
| title_short | Synthesis and structures of calcium and strontium 2,4-di-tert-butylphenolates and their reactivity towards the amine co-initiated ring-opening polymerisation of rac-lactide. |
| title_sort | synthesis and structures of calcium and strontium 2 4 di tert butylphenolates and their reactivity towards the amine co initiated ring opening polymerisation of rac lactide |
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