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Tuning π-Acceptor/σ-Donor Ratio of the 2-Isocyanoazulene Ligand: Non-Fluorinated Rival of Pentafluorophenyl Isocyanide and Trifluorovinyl Isocyanide Discovered
Isocyanoazulenes (CNAz) constitute a relatively new class of isocyanoarenes that offers rich structural and electronic diversification of the organic isocyanide ligand platform. This article considers a series of 2-isocyano-1,3-X(2)-azulene ligands (X = H, Me, CO(2)Et, Br, and CN) and the correspond...
Autores principales: | , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7918097/ https://www.ncbi.nlm.nih.gov/pubmed/33673291 http://dx.doi.org/10.3390/molecules26040981 |
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author | Hart, Mason D. Meyers, John J. Wood, Zachary A. Nakakita, Toshinori Applegate, Jason C. Erickson, Nathan R. Gerasimchuk, Nikolay N. Barybin, Mikhail V. |
author_facet | Hart, Mason D. Meyers, John J. Wood, Zachary A. Nakakita, Toshinori Applegate, Jason C. Erickson, Nathan R. Gerasimchuk, Nikolay N. Barybin, Mikhail V. |
author_sort | Hart, Mason D. |
collection | PubMed |
description | Isocyanoazulenes (CNAz) constitute a relatively new class of isocyanoarenes that offers rich structural and electronic diversification of the organic isocyanide ligand platform. This article considers a series of 2-isocyano-1,3-X(2)-azulene ligands (X = H, Me, CO(2)Et, Br, and CN) and the corresponding zero-valent complexes thereof, [(OC)(5)Cr(2-isocyano-1,3-X(2)-azulene)]. Air- and thermally stable, X-ray structurally characterized 2-isocyano-1,3-dimethylazulene may be viewed as a non-benzenoid aromatic congener of 2,6-dimethyphenyl isocyanide (2,6-xylyl isocyanide), a longtime “workhorse” aryl isocyanide ligand in coordination chemistry. Single crystal X-ray crystallographic {Cr–CNAz bond distances}, cyclic voltametric {E(1/2)(Cr(0/1+))}, (13)C NMR {δ((13)CN), δ((13)CO)}, UV-vis {dπ(Cr) → pπ*(CNAz) Metal-to-Ligand Charge Transfer}, and FTIR {ν(N)(≡)(C), ν(C)(≡)(O), k(C)(≡)(O)} analyses of the [(OC)(5)Cr(2-isocyano-1,3-X(2)-azulene)] complexes provided a multifaceted, quantitative assessment of the π-acceptor/σ-donor characteristics of the above five 2-isocyanoazulenes. In particular, the following inverse linear relationships were documented: δ((13)CO(trans)) vs. δ((13)CN), δ((13)CO(cis)) vs. δ((13)CN), and δ((13)CO(trans)) vs. k(C)(≡)(O,trans) force constant. Remarkably, the net electron withdrawing capability of the 2-isocyano-1,3-dicyanoazulene ligand rivals those of perfluorinated isocyanides CNC(6)F(5) and CNC(2)F(3). |
format | Online Article Text |
id | pubmed-7918097 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-79180972021-03-02 Tuning π-Acceptor/σ-Donor Ratio of the 2-Isocyanoazulene Ligand: Non-Fluorinated Rival of Pentafluorophenyl Isocyanide and Trifluorovinyl Isocyanide Discovered Hart, Mason D. Meyers, John J. Wood, Zachary A. Nakakita, Toshinori Applegate, Jason C. Erickson, Nathan R. Gerasimchuk, Nikolay N. Barybin, Mikhail V. Molecules Article Isocyanoazulenes (CNAz) constitute a relatively new class of isocyanoarenes that offers rich structural and electronic diversification of the organic isocyanide ligand platform. This article considers a series of 2-isocyano-1,3-X(2)-azulene ligands (X = H, Me, CO(2)Et, Br, and CN) and the corresponding zero-valent complexes thereof, [(OC)(5)Cr(2-isocyano-1,3-X(2)-azulene)]. Air- and thermally stable, X-ray structurally characterized 2-isocyano-1,3-dimethylazulene may be viewed as a non-benzenoid aromatic congener of 2,6-dimethyphenyl isocyanide (2,6-xylyl isocyanide), a longtime “workhorse” aryl isocyanide ligand in coordination chemistry. Single crystal X-ray crystallographic {Cr–CNAz bond distances}, cyclic voltametric {E(1/2)(Cr(0/1+))}, (13)C NMR {δ((13)CN), δ((13)CO)}, UV-vis {dπ(Cr) → pπ*(CNAz) Metal-to-Ligand Charge Transfer}, and FTIR {ν(N)(≡)(C), ν(C)(≡)(O), k(C)(≡)(O)} analyses of the [(OC)(5)Cr(2-isocyano-1,3-X(2)-azulene)] complexes provided a multifaceted, quantitative assessment of the π-acceptor/σ-donor characteristics of the above five 2-isocyanoazulenes. In particular, the following inverse linear relationships were documented: δ((13)CO(trans)) vs. δ((13)CN), δ((13)CO(cis)) vs. δ((13)CN), and δ((13)CO(trans)) vs. k(C)(≡)(O,trans) force constant. Remarkably, the net electron withdrawing capability of the 2-isocyano-1,3-dicyanoazulene ligand rivals those of perfluorinated isocyanides CNC(6)F(5) and CNC(2)F(3). MDPI 2021-02-12 /pmc/articles/PMC7918097/ /pubmed/33673291 http://dx.doi.org/10.3390/molecules26040981 Text en © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Hart, Mason D. Meyers, John J. Wood, Zachary A. Nakakita, Toshinori Applegate, Jason C. Erickson, Nathan R. Gerasimchuk, Nikolay N. Barybin, Mikhail V. Tuning π-Acceptor/σ-Donor Ratio of the 2-Isocyanoazulene Ligand: Non-Fluorinated Rival of Pentafluorophenyl Isocyanide and Trifluorovinyl Isocyanide Discovered |
title | Tuning π-Acceptor/σ-Donor Ratio of the 2-Isocyanoazulene Ligand: Non-Fluorinated Rival of Pentafluorophenyl Isocyanide and Trifluorovinyl Isocyanide Discovered |
title_full | Tuning π-Acceptor/σ-Donor Ratio of the 2-Isocyanoazulene Ligand: Non-Fluorinated Rival of Pentafluorophenyl Isocyanide and Trifluorovinyl Isocyanide Discovered |
title_fullStr | Tuning π-Acceptor/σ-Donor Ratio of the 2-Isocyanoazulene Ligand: Non-Fluorinated Rival of Pentafluorophenyl Isocyanide and Trifluorovinyl Isocyanide Discovered |
title_full_unstemmed | Tuning π-Acceptor/σ-Donor Ratio of the 2-Isocyanoazulene Ligand: Non-Fluorinated Rival of Pentafluorophenyl Isocyanide and Trifluorovinyl Isocyanide Discovered |
title_short | Tuning π-Acceptor/σ-Donor Ratio of the 2-Isocyanoazulene Ligand: Non-Fluorinated Rival of Pentafluorophenyl Isocyanide and Trifluorovinyl Isocyanide Discovered |
title_sort | tuning π-acceptor/σ-donor ratio of the 2-isocyanoazulene ligand: non-fluorinated rival of pentafluorophenyl isocyanide and trifluorovinyl isocyanide discovered |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7918097/ https://www.ncbi.nlm.nih.gov/pubmed/33673291 http://dx.doi.org/10.3390/molecules26040981 |
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