Anion‐Induced Urea Deprotonation
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- 1 January 2005
- journal article
- research article
- Published by Wiley in Chemistry – A European Journal
- Vol. 11 (10) , 3097-3104
- https://doi.org/10.1002/chem.200401049
Abstract
The urea-based receptor 1 (1-(7-nitrobenzo[1,2,5]oxadiazol-4-yl)-3-(4-nitrophenyl)urea, LH), interacts with X− ions in MeCN, according to two consecutive steps: 1) formation of a hydrogen-bond complex [LH⋅⋅⋅X]−; 2) deprotonation of LH to give L− and [HX2]−, as shown by spectrophotometric and 1H NMR titration experiments. Step 2) takes place with more basic anions (fluoride, carboxylates, dihydrogenphosphate), while less basic anions (Cl−, NO2−, NO3−) do not induce proton transfer. On crystallisation from a solution containing LH and excess Bu4NF, the tetrabutylammonium salt of the deprotonated urea derivative (Bu4N[L]) was isolated and its crystal and molecular structure determined.Keywords
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