N-Nitroso- and N-Nitraminotetrazoles

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Abstract
N-Nitroso- (5a,c) and N-nitraminotetrazoles (6a − c) were synthesized from the corresponding aminotetrazoles (3a − c) either by the direct nitration with acetic anhydride/HNO3 or by dehydration of the corresponding nitrates (4a − c) with concentrated sulfuric acid. The conversion of the N-nitrosoaminotetrazoles (5a,c) with peroxytrifluoroacetic acid (CF3CO3H) yielded the corresponding nitramines in high yield (6a (82%), 6c (80%)). The N-nitroso- (5a,c) and N-nitraminotetrazoles (6a − c) have been fully characterized by vibrational (IR, Raman) and multinuclear NMR spectroscopy (14N/15N, 1H, 13C), mass spectrometry, and elemental analysis. A detailed discussion of the 15N chemical shifts and 1H−15N coupling constants is given. The molecular structures in the solid state were determined by single-crystal X-ray diffraction (3a,c; 5a,c; 6a − c) and a detailed discussion of the molecular structures will be presented. Furthermore, the structure and bonding as well as N,N rotational barriers are discussed on the basis of theoretically obtained data (B3LYP/6-31G(d,p), NBO analysis). In the case of two N-nitraminotetrazoles (6a,c) the physicochemical properties (e.g., D, P, ΔfH°) were evaluated. The heat of formation was calculated to be positive for 6a and 6c (+2.8 and +85.2 kcal mol-1, respectively) and the calculated detonation velocity with 5988 (6a) and 7181 (6c) m s-1 reaches values of TNT and nitroglycerin.