Structural Elucidation of the Triethylammonium Betaine of Squaric Acid
Betaines of squaric acid have gained research interest because of their structural and spectral properties. We elucidated the crystal and molecular structure of the triethylammonium betaine of squaric acid (<b>1</b>) by X-ray crystallography, IR, and NMR spectroscopy augmented by Hirshfe...
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MDPI AG
2023-10-01
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| Online Access: | https://www.mdpi.com/1422-8599/2023/4/M1737 |
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| author | Paul R. Palme Richard Goddard Markus Leutzsch Adrian Richter Peter Imming Rüdiger W. Seidel |
| author_facet | Paul R. Palme Richard Goddard Markus Leutzsch Adrian Richter Peter Imming Rüdiger W. Seidel |
| author_sort | Paul R. Palme |
| collection | DOAJ |
| description | Betaines of squaric acid have gained research interest because of their structural and spectral properties. We elucidated the crystal and molecular structure of the triethylammonium betaine of squaric acid (<b>1</b>) by X-ray crystallography, IR, and NMR spectroscopy augmented by Hirshfeld surface analysis and DFT calculations. The crystal structure determination using Hirshfeld atom refinement reveals that the resonance hybrid structure with partial enolate character of the two lateral squaric acid C=O groups describes <b>1</b> best. The solid-state supramolecular structure features weak intermolecular C−H···O hydrogen bonds. The number of C=O bands in the IR spectrum in the solid-state is consistent with local <i>C</i><sub>2v</sub> symmetry of the squaric acid residue in <b>1</b>. The <sup>13</sup>C NMR signals of this group in solution were assigned based on 2D NMR experiments and computational prediction using the Gauge-Independent Atom Orbital (GIAO) method. The present study provides the first structural characterization of a betaine of squaric acid containing a four-coordinate nitrogen atom directly attached to the four-membered ring. |
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| issn | 1422-8599 |
| language | English |
| last_indexed | 2024-03-08T20:31:03Z |
| publishDate | 2023-10-01 |
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| spelling | doaj.art-8bf0b5f28b364669934109a92915eb7f2023-12-22T14:27:03ZengMDPI AGMolbank1422-85992023-10-0120234M173710.3390/M1737Structural Elucidation of the Triethylammonium Betaine of Squaric AcidPaul R. Palme0Richard Goddard1Markus Leutzsch2Adrian Richter3Peter Imming4Rüdiger W. Seidel5Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Straße 4, 06120 Halle (Saale), GermanyMax-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, GermanyMax-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, GermanyInstitut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Straße 4, 06120 Halle (Saale), GermanyInstitut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Straße 4, 06120 Halle (Saale), GermanyInstitut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Straße 4, 06120 Halle (Saale), GermanyBetaines of squaric acid have gained research interest because of their structural and spectral properties. We elucidated the crystal and molecular structure of the triethylammonium betaine of squaric acid (<b>1</b>) by X-ray crystallography, IR, and NMR spectroscopy augmented by Hirshfeld surface analysis and DFT calculations. The crystal structure determination using Hirshfeld atom refinement reveals that the resonance hybrid structure with partial enolate character of the two lateral squaric acid C=O groups describes <b>1</b> best. The solid-state supramolecular structure features weak intermolecular C−H···O hydrogen bonds. The number of C=O bands in the IR spectrum in the solid-state is consistent with local <i>C</i><sub>2v</sub> symmetry of the squaric acid residue in <b>1</b>. The <sup>13</sup>C NMR signals of this group in solution were assigned based on 2D NMR experiments and computational prediction using the Gauge-Independent Atom Orbital (GIAO) method. The present study provides the first structural characterization of a betaine of squaric acid containing a four-coordinate nitrogen atom directly attached to the four-membered ring.https://www.mdpi.com/1422-8599/2023/4/M1737squaric acidbetainecrystal structureHirshfeld surface analysisIR spectroscopyNMR spectroscopy |
| spellingShingle | Paul R. Palme Richard Goddard Markus Leutzsch Adrian Richter Peter Imming Rüdiger W. Seidel Structural Elucidation of the Triethylammonium Betaine of Squaric Acid Molbank squaric acid betaine crystal structure Hirshfeld surface analysis IR spectroscopy NMR spectroscopy |
| title | Structural Elucidation of the Triethylammonium Betaine of Squaric Acid |
| title_full | Structural Elucidation of the Triethylammonium Betaine of Squaric Acid |
| title_fullStr | Structural Elucidation of the Triethylammonium Betaine of Squaric Acid |
| title_full_unstemmed | Structural Elucidation of the Triethylammonium Betaine of Squaric Acid |
| title_short | Structural Elucidation of the Triethylammonium Betaine of Squaric Acid |
| title_sort | structural elucidation of the triethylammonium betaine of squaric acid |
| topic | squaric acid betaine crystal structure Hirshfeld surface analysis IR spectroscopy NMR spectroscopy |
| url | https://www.mdpi.com/1422-8599/2023/4/M1737 |
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