A zwitterion produced by a strong intramolecular N→B interaction in 1-hydroxy-2-(pyridin-2-ylcarbonyl)benzo[d][1,2,3]diazaborinine
| Autor: | Evan A. Sarina, Marilyn M. Olmstead, Divya Kanichar, Michael P. Groziak |
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| Rok vydání: | 2015 |
| Předmět: |
Chemistry
Stereochemistry Crystal structure Condensed Matter Physics Resonance (chemistry) Condensation reaction Inorganic Chemistry chemistry.chemical_compound Zwitterion Intramolecular force Materials Chemistry Proton NMR Hydrogen–deuterium exchange Lewis acids and bases Physical and Theoretical Chemistry |
| Zdroj: | Acta crystallographica. Section C, Structural chemistry. 71(Pt 12) |
| ISSN: | 2053-2296 |
| Popis: | 2-Acylated 2,3,1-benzodiazaborines can display unusual structures and reactivities. The crystal structure analysis of the boron heterocycle obtained by condensing 2-formylphenylboronic acid and picolinohydrazide reveals it to be an N→B-chelated zwitterionic tetracycle (systematic name: 1-hydroxy-11-oxo-9,10,17λ5-triaza-1λ4-boratetracyclo[8.7.0.02,7.012,17]heptadeca-3,5,7,12,14,16-hexaen-17-ylium-1-uide), C13H10BN3O2, produced by the intramolecular addition of the Lewis basic picolinoyl N atom of 1-hydroxy-2-(pyridin-2-ylcarbonyl)benzo[d][1,2,3]diazaborinine to the boron heterocycle B atom acting as a Lewis acid. Neither of the other two pyridinylcarbonyl isomers (viz. nicotinoyl and isonicotinoyl) are able to adopt such a structure for geometric reasons. A favored yet reversible chelation equilibrium provides an explanation for the slow D2O exchange observed for the OH resonance in the1H NMR spectrum, as well as for its unusual upfield chemical shift. Deuterium exchange may take place solely in the minor open (unchelated) species present in solution. |
| Databáze: | OpenAIRE |
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