Formation of Alternating trans-A-alt-B Copolymers through Ring-Opening Metathesis Polymerization Initiated by Molybdenum Imido Alkylidene Complexes
Ring-opening metathesis polymerization (ROMP) is used to prepare trans-poly(A-alt-B) polymers from a 1:1 mixture of A and B where A is a cyclic olefin such as cyclooctene (A[subscript 1]) or cycloheptene (A[subscript 2]) and B is a large norbornadiene or norbornene derivative such as 2,3-dicarbometh...
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| Format: | Article |
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American Chemical Society (ACS)
2016
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| Online Access: | http://hdl.handle.net/1721.1/105182 https://orcid.org/0000-0002-1788-4100 https://orcid.org/0000-0002-7405-6811 https://orcid.org/0000-0001-5827-3552 |
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| author | Jeong, Hyangsoo John, Jeremy M Schrock, Richard Royce |
| author2 | Massachusetts Institute of Technology. Department of Chemistry |
| author_facet | Massachusetts Institute of Technology. Department of Chemistry Jeong, Hyangsoo John, Jeremy M Schrock, Richard Royce |
| author_sort | Jeong, Hyangsoo |
| collection | MIT |
| description | Ring-opening metathesis polymerization (ROMP) is used to prepare trans-poly(A-alt-B) polymers from a 1:1 mixture of A and B where A is a cyclic olefin such as cyclooctene (A[subscript 1]) or cycloheptene (A[subscript 2]) and B is a large norbornadiene or norbornene derivative such as 2,3-dicarbomethoxy-7-isopropylidenenorbornadiene (B[subscript 1]) or dimethylspirobicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate-7,1'cyclopropane (B[subscript 2]). The most successful initiators that were
examined are of the type Mo(NR)(CHCMe[subscript 2]Ph)[OCMe(CF[subscript 3])[subscript 2]][subscript 2] (R = 2,6-Me[subscript 2]C[subscript 6]H[subscript 3] (1) or 2,6-iPr[subscript 2]C[subscript 6]H[subscript 3] (2)). The trans configuration of the AB linkages is proposed to result from the steric demand of B. Both anti-MB and syn-MB alkylidenes are observed during the copolymerization, where B was last inserted into a Mo=C bond, although anti-MB dominates as the reaction
proceeds. Anti-MB is lower in energy than syn-MB, does not react readily with either A or B, and interconverts slowly with syn-MB through rotation about the Mo=C bond. Syn-MB does not readily react with B, but it does react slowly with A (rate constant ~1 M[superscript -1] s
[superscript -1]) to give anti-MA and one trans-AB linkage. Anti-MA then reacts with B (rate constant ~300 M[superscript -1] s[superscript -1] or larger) to give syn-MB and the second trans-AB linkage. The reaction has been modeled using experimental data in order to obtain the estimated rate constants above. The reaction between anti-MA and A is proposed to give rise to AA linkages, but AA dyads can amount to <5%. Several other possible A and B monomers, initiators, and conditions were explored. |
| first_indexed | 2024-09-23T13:06:36Z |
| format | Article |
| id | mit-1721.1/105182 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T13:06:36Z |
| publishDate | 2016 |
| publisher | American Chemical Society (ACS) |
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| spelling | mit-1721.1/1051822022-10-01T13:06:44Z Formation of Alternating trans-A-alt-B Copolymers through Ring-Opening Metathesis Polymerization Initiated by Molybdenum Imido Alkylidene Complexes Jeong, Hyangsoo John, Jeremy M Schrock, Richard Royce Massachusetts Institute of Technology. Department of Chemistry Schrock, Richard Royce Jeong, Hyangsoo John, Jeremy M Schrock, Richard Royce Ring-opening metathesis polymerization (ROMP) is used to prepare trans-poly(A-alt-B) polymers from a 1:1 mixture of A and B where A is a cyclic olefin such as cyclooctene (A[subscript 1]) or cycloheptene (A[subscript 2]) and B is a large norbornadiene or norbornene derivative such as 2,3-dicarbomethoxy-7-isopropylidenenorbornadiene (B[subscript 1]) or dimethylspirobicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate-7,1'cyclopropane (B[subscript 2]). The most successful initiators that were examined are of the type Mo(NR)(CHCMe[subscript 2]Ph)[OCMe(CF[subscript 3])[subscript 2]][subscript 2] (R = 2,6-Me[subscript 2]C[subscript 6]H[subscript 3] (1) or 2,6-iPr[subscript 2]C[subscript 6]H[subscript 3] (2)). The trans configuration of the AB linkages is proposed to result from the steric demand of B. Both anti-MB and syn-MB alkylidenes are observed during the copolymerization, where B was last inserted into a Mo=C bond, although anti-MB dominates as the reaction proceeds. Anti-MB is lower in energy than syn-MB, does not react readily with either A or B, and interconverts slowly with syn-MB through rotation about the Mo=C bond. Syn-MB does not readily react with B, but it does react slowly with A (rate constant ~1 M[superscript -1] s [superscript -1]) to give anti-MA and one trans-AB linkage. Anti-MA then reacts with B (rate constant ~300 M[superscript -1] s[superscript -1] or larger) to give syn-MB and the second trans-AB linkage. The reaction has been modeled using experimental data in order to obtain the estimated rate constants above. The reaction between anti-MA and A is proposed to give rise to AA linkages, but AA dyads can amount to <5%. Several other possible A and B monomers, initiators, and conditions were explored. United States. Dept. of Energy (Grant DE-FG02-86ER13564) 2016-11-03T18:28:58Z 2016-11-03T18:28:58Z 2015-10 Article http://purl.org/eprint/type/JournalArticle 0276-7333 1520-6041 http://hdl.handle.net/1721.1/105182 Jeong, Hyangsoo, Jeremy M. John, and Richard R. Schrock. “Formation of Alternating trans-A-alt-B Copolymers through Ring-Opening Metathesis Polymerization Initiated by Molybdenum Imido Alkylidene Complexes.” Organometallics 34.20 (2015): 5136–5145. https://orcid.org/0000-0002-1788-4100 https://orcid.org/0000-0002-7405-6811 https://orcid.org/0000-0001-5827-3552 en_US http://pubs.acs.org/doi/full/10.1021/acs.organomet.5b00709 Organometallics Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Chemical Society (ACS) Prof. Schrock |
| spellingShingle | Jeong, Hyangsoo John, Jeremy M Schrock, Richard Royce Formation of Alternating trans-A-alt-B Copolymers through Ring-Opening Metathesis Polymerization Initiated by Molybdenum Imido Alkylidene Complexes |
| title | Formation of Alternating trans-A-alt-B Copolymers through Ring-Opening Metathesis Polymerization Initiated by Molybdenum Imido Alkylidene Complexes |
| title_full | Formation of Alternating trans-A-alt-B Copolymers through Ring-Opening Metathesis Polymerization Initiated by Molybdenum Imido Alkylidene Complexes |
| title_fullStr | Formation of Alternating trans-A-alt-B Copolymers through Ring-Opening Metathesis Polymerization Initiated by Molybdenum Imido Alkylidene Complexes |
| title_full_unstemmed | Formation of Alternating trans-A-alt-B Copolymers through Ring-Opening Metathesis Polymerization Initiated by Molybdenum Imido Alkylidene Complexes |
| title_short | Formation of Alternating trans-A-alt-B Copolymers through Ring-Opening Metathesis Polymerization Initiated by Molybdenum Imido Alkylidene Complexes |
| title_sort | formation of alternating trans a alt b copolymers through ring opening metathesis polymerization initiated by molybdenum imido alkylidene complexes |
| url | http://hdl.handle.net/1721.1/105182 https://orcid.org/0000-0002-1788-4100 https://orcid.org/0000-0002-7405-6811 https://orcid.org/0000-0001-5827-3552 |
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