<i>Meta</i>-Xylene-Based Diamines with Protected Benzyl Sites: Potential NCN Pincer Ligands with Tunable Steric Profiles
Bulky NCN aryl-diamides featuring methyl groups in the benzyl positions were synthesized with the aim of creating a new class of <i>meta</i>-xylene-based trianionic pincer ligands where the common decomposition pathway of metal pincer complexes via C-H activation is prevented. Sterically...
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MDPI AG
2025-03-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/30/6/1331 |
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| author | Tamina Z. Kirsch Toren Hynes Jason D. Masuda Saurabh S. Chitnis |
| author_facet | Tamina Z. Kirsch Toren Hynes Jason D. Masuda Saurabh S. Chitnis |
| author_sort | Tamina Z. Kirsch |
| collection | DOAJ |
| description | Bulky NCN aryl-diamides featuring methyl groups in the benzyl positions were synthesized with the aim of creating a new class of <i>meta</i>-xylene-based trianionic pincer ligands where the common decomposition pathway of metal pincer complexes via C-H activation is prevented. Sterically demanding substituents on the ligands furthermore provide steric protection of the metal centre and can help prevent the dimerization of the complexes. While a double deprotonation of the ligands and the formation of a dilithium salt was straightforward, difficulties were encountered when attempting to deprotonate the <i>ipso</i>-C<i>H</i> proton on the central aryl ring to yield trianionic ligands. This stands in contrast to related pincer ligands without methyl groups in the benzylic positions. Experimental and theoretical investigations led to the conclusion that the challenges encountered when attempting the third deprotonation are likely caused by an interplay of increased electron density at the nitrogen atoms and steric hindrance. Both effects originate in the introduction of methyl groups in the benzylic positions, which make the targeted proton less accessible. These results provide further insight into the impact of methyl groups in the benzyl positions on both steric and electronic properties of NCN pincer ligands, which may find utility in coordination chemistry applications where metalation can be achieved by direct C-H activation rather than requiring triple deprotonation. |
| format | Article |
| id | doaj-art-c079a9c912bc4c088e39ac1061c87d45 |
| institution | OA Journals |
| issn | 1420-3049 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj-art-c079a9c912bc4c088e39ac1061c87d452025-08-20T01:49:05ZengMDPI AGMolecules1420-30492025-03-01306133110.3390/molecules30061331<i>Meta</i>-Xylene-Based Diamines with Protected Benzyl Sites: Potential NCN Pincer Ligands with Tunable Steric ProfilesTamina Z. Kirsch0Toren Hynes1Jason D. Masuda2Saurabh S. Chitnis3Department of Chemistry, Dalhousie University, 6243 Alumni Crescent, Halifax, NS B3H 4R2, CanadaDepartment of Chemistry, Dalhousie University, 6243 Alumni Crescent, Halifax, NS B3H 4R2, CanadaDepartment of Chemistry, Saint Mary’s University, 923 Robie Street, Halifax, NS B3H 3C3, CanadaDepartment of Chemistry, Dalhousie University, 6243 Alumni Crescent, Halifax, NS B3H 4R2, CanadaBulky NCN aryl-diamides featuring methyl groups in the benzyl positions were synthesized with the aim of creating a new class of <i>meta</i>-xylene-based trianionic pincer ligands where the common decomposition pathway of metal pincer complexes via C-H activation is prevented. Sterically demanding substituents on the ligands furthermore provide steric protection of the metal centre and can help prevent the dimerization of the complexes. While a double deprotonation of the ligands and the formation of a dilithium salt was straightforward, difficulties were encountered when attempting to deprotonate the <i>ipso</i>-C<i>H</i> proton on the central aryl ring to yield trianionic ligands. This stands in contrast to related pincer ligands without methyl groups in the benzylic positions. Experimental and theoretical investigations led to the conclusion that the challenges encountered when attempting the third deprotonation are likely caused by an interplay of increased electron density at the nitrogen atoms and steric hindrance. Both effects originate in the introduction of methyl groups in the benzylic positions, which make the targeted proton less accessible. These results provide further insight into the impact of methyl groups in the benzyl positions on both steric and electronic properties of NCN pincer ligands, which may find utility in coordination chemistry applications where metalation can be achieved by direct C-H activation rather than requiring triple deprotonation.https://www.mdpi.com/1420-3049/30/6/1331pincer ligandscoordination chemistrybismuthstructure |
| spellingShingle | Tamina Z. Kirsch Toren Hynes Jason D. Masuda Saurabh S. Chitnis <i>Meta</i>-Xylene-Based Diamines with Protected Benzyl Sites: Potential NCN Pincer Ligands with Tunable Steric Profiles Molecules pincer ligands coordination chemistry bismuth structure |
| title | <i>Meta</i>-Xylene-Based Diamines with Protected Benzyl Sites: Potential NCN Pincer Ligands with Tunable Steric Profiles |
| title_full | <i>Meta</i>-Xylene-Based Diamines with Protected Benzyl Sites: Potential NCN Pincer Ligands with Tunable Steric Profiles |
| title_fullStr | <i>Meta</i>-Xylene-Based Diamines with Protected Benzyl Sites: Potential NCN Pincer Ligands with Tunable Steric Profiles |
| title_full_unstemmed | <i>Meta</i>-Xylene-Based Diamines with Protected Benzyl Sites: Potential NCN Pincer Ligands with Tunable Steric Profiles |
| title_short | <i>Meta</i>-Xylene-Based Diamines with Protected Benzyl Sites: Potential NCN Pincer Ligands with Tunable Steric Profiles |
| title_sort | i meta i xylene based diamines with protected benzyl sites potential ncn pincer ligands with tunable steric profiles |
| topic | pincer ligands coordination chemistry bismuth structure |
| url | https://www.mdpi.com/1420-3049/30/6/1331 |
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