Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene
Molybdenum complexes with the general formula Mo(NR)(CHR′)(OR″)(Cl)(MeCN) (R = t-Bu or 1-adamantyl; OR″ = a 2,6-terphenoxide) recently have been found to be highly active catalysts for cross-metathesis reactions between Z-internal olefins and Z-1,2-dichloroethylene or Z-(CF₃)CH═CH(CF₃). In this pape...
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| Format: | Article |
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American Chemical Society (ACS)
2018
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| Online Access: | http://hdl.handle.net/1721.1/115116 https://orcid.org/0000-0003-1913-7173 https://orcid.org/0000-0001-6530-3852 https://orcid.org/0000-0001-5827-3552 |
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| author | Hoveyda, Amir Lam, Jonathan K Zhu, Congqing Bukhryakov, Konstantin Mueller, Peter Schrock, Richard Royce |
| author2 | Massachusetts Institute of Technology. Department of Chemistry |
| author_facet | Massachusetts Institute of Technology. Department of Chemistry Hoveyda, Amir Lam, Jonathan K Zhu, Congqing Bukhryakov, Konstantin Mueller, Peter Schrock, Richard Royce |
| author_sort | Hoveyda, Amir |
| collection | MIT |
| description | Molybdenum complexes with the general formula Mo(NR)(CHR′)(OR″)(Cl)(MeCN) (R = t-Bu or 1-adamantyl; OR″ = a 2,6-terphenoxide) recently have been found to be highly active catalysts for cross-metathesis reactions between Z-internal olefins and Z-1,2-dichloroethylene or Z-(CF₃)CH═CH(CF₃). In this paper we report methods of synthesizing new potential catalysts with the general formula M(NR)(CHR′)(OR″)(Cl)(L) in which M = Mo or W, NR = N-2,6-diisopropylphenyl or NC6F5, and L is a phosphine, a pyridine, or a nitrile. We also test and compare all catalysts in the cross-metathesis of Z-1,2-dichloroethylene and cyclooctene. Our investigations indicate that tungsten complexes are inactive in the test reaction either because the donor is bound too strongly or because acetonitrile inserts into a W═C bond. The acetonitrile or pivalonitrile Mo(NR)(CHR′)(OR″)(Cl)(L) complexes are found to be especially reactive because the 14e Mo(NR)(CHR′)(OR″)Cl core is accessible through dissociation of the nitrile to a significant extent. Pivalonitrile can be removed (>95%) from Mo(NAr)(CHCMe₂Ph)(OHMT)(Cl)(t-BuCN) (Ar = 2,6-diisopropylphenyl; OHMT = 2,6-dimesitylphenoxide) to give 14e Mo(NAr)(CHCMe₂Ph)(OHMT)Cl in solution as a mixture of syn and anti (60:40 at 0.015 M) nitrile-free isomers, but these 14e complexes have not yet been isolated in pure form. The syn isomer of Mo(NAr)(CHCMe₂Ph)(OHMT)Cl binds pivalonitrile most strongly. Other Mo(NR)(CHR′)(OR″)(Cl)(L) complexes can be activated through addition of B(C₆F₅)₃. High stereoselectivities (>98% Z,Z) of ClCH═CH(CH₂)₆CH═CHCl are not restricted to tert-butylimido or adamantylimido complexes; 96.2% Z selectivity is observed with boron-activated Mo(NC₆F₅)(CHR′)(OHIPT)(Cl)(PPhMe₂). So far no Mo═CHCl complexes, which are required intermediates in the test reaction, have been observed in NMR studies at room temperature. |
| first_indexed | 2024-09-23T11:43:24Z |
| format | Article |
| id | mit-1721.1/115116 |
| institution | Massachusetts Institute of Technology |
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| spelling | mit-1721.1/1151162022-09-27T21:29:41Z Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene Hoveyda, Amir Lam, Jonathan K Zhu, Congqing Bukhryakov, Konstantin Mueller, Peter Schrock, Richard Royce Massachusetts Institute of Technology. Department of Chemistry Schrock, Richard Royce Lam, Jonathan K Zhu, Congqing Bukhryakov, Konstantin Mueller, Peter Schrock, Richard Royce Molybdenum complexes with the general formula Mo(NR)(CHR′)(OR″)(Cl)(MeCN) (R = t-Bu or 1-adamantyl; OR″ = a 2,6-terphenoxide) recently have been found to be highly active catalysts for cross-metathesis reactions between Z-internal olefins and Z-1,2-dichloroethylene or Z-(CF₃)CH═CH(CF₃). In this paper we report methods of synthesizing new potential catalysts with the general formula M(NR)(CHR′)(OR″)(Cl)(L) in which M = Mo or W, NR = N-2,6-diisopropylphenyl or NC6F5, and L is a phosphine, a pyridine, or a nitrile. We also test and compare all catalysts in the cross-metathesis of Z-1,2-dichloroethylene and cyclooctene. Our investigations indicate that tungsten complexes are inactive in the test reaction either because the donor is bound too strongly or because acetonitrile inserts into a W═C bond. The acetonitrile or pivalonitrile Mo(NR)(CHR′)(OR″)(Cl)(L) complexes are found to be especially reactive because the 14e Mo(NR)(CHR′)(OR″)Cl core is accessible through dissociation of the nitrile to a significant extent. Pivalonitrile can be removed (>95%) from Mo(NAr)(CHCMe₂Ph)(OHMT)(Cl)(t-BuCN) (Ar = 2,6-diisopropylphenyl; OHMT = 2,6-dimesitylphenoxide) to give 14e Mo(NAr)(CHCMe₂Ph)(OHMT)Cl in solution as a mixture of syn and anti (60:40 at 0.015 M) nitrile-free isomers, but these 14e complexes have not yet been isolated in pure form. The syn isomer of Mo(NAr)(CHCMe₂Ph)(OHMT)Cl binds pivalonitrile most strongly. Other Mo(NR)(CHR′)(OR″)(Cl)(L) complexes can be activated through addition of B(C₆F₅)₃. High stereoselectivities (>98% Z,Z) of ClCH═CH(CH₂)₆CH═CHCl are not restricted to tert-butylimido or adamantylimido complexes; 96.2% Z selectivity is observed with boron-activated Mo(NC₆F₅)(CHR′)(OHIPT)(Cl)(PPhMe₂). So far no Mo═CHCl complexes, which are required intermediates in the test reaction, have been observed in NMR studies at room temperature. National Institutes of Health (U.S.) (Award GM-59426) National Science Foundation (U.S.) (Grant CHE-1463707) National Science Foundation (U.S.) (Grant CHE-0946721) 2018-04-30T19:47:25Z 2018-04-30T19:47:25Z 2016-12 2016-10 Article http://purl.org/eprint/type/JournalArticle 0002-7863 1520-5126 http://hdl.handle.net/1721.1/115116 Lam, Jonathan K. et al. “Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene.” Journal of the American Chemical Society 138, 48 (November 2016): 15774–15783 © 2016 American Chemical Society https://orcid.org/0000-0003-1913-7173 https://orcid.org/0000-0001-6530-3852 https://orcid.org/0000-0001-5827-3552 en_US http://dx.doi.org/10.1021/jacs.6b10499 Journal of the American Chemical Society 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 via Erja Kajosalo |
| spellingShingle | Hoveyda, Amir Lam, Jonathan K Zhu, Congqing Bukhryakov, Konstantin Mueller, Peter Schrock, Richard Royce Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene |
| title | Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene |
| title_full | Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene |
| title_fullStr | Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene |
| title_full_unstemmed | Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene |
| title_short | Synthesis and Evaluation of Molybdenum and Tungsten Monoaryloxide Halide Alkylidene Complexes for Z-Selective Cross-Metathesis of Cyclooctene and Z-1,2-Dichloroethylene |
| title_sort | synthesis and evaluation of molybdenum and tungsten monoaryloxide halide alkylidene complexes for z selective cross metathesis of cyclooctene and z 1 2 dichloroethylene |
| url | http://hdl.handle.net/1721.1/115116 https://orcid.org/0000-0003-1913-7173 https://orcid.org/0000-0001-6530-3852 https://orcid.org/0000-0001-5827-3552 |
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