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Protonation of Nitramines: Where Does the Proton Go?
Author(s) -
Saal Thomas,
Rahm Martin,
Christe Karl O.,
Haiges Ralf
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201705397
Subject(s) - protonation , chemistry , anhydrous , counterion , nuclear magnetic resonance spectroscopy , proton , spectroscopy , inorganic chemistry , medicinal chemistry , crystallography , ion , organic chemistry , physics , quantum mechanics
The reactions of nitramine, N ‐methyl nitramine, and N , N ‐dimethyl nitramine with anhydrous HF and the superacids HF/MF 5 (M=As, Sb) were investigated at temperatures below −40 °C. In solution, exclusive O‐protonation was observed by multinuclear NMR spectroscopy. Whereas no solid product could be isolated from the neat HF solutions even at −78 °C, in the HF/MF 5 systems, protonated nitramine MF 6 − salts were isolated for the first time as moisture‐sensitive solids that decompose at temperatures above −40 °C. In the solid state, depending on the counterion, O‐protonated or N‐protonated cations can be formed, in accord with theoretical calculations which show that the energy differences between O‐protonation and N‐protonation are very small. The salts [H 2 N‐NO 2 H][AsF 6 ], [H 3 N‐NO 2 ][SbF 6 ], [MeHNNO 2 H][SbF 6 ], and [Me 2 NNO 2 H][SbF 6 ] were characterized by their X‐ray crystal structures.