Structure of N,4-dinitroaniline and its complex with sulfolane at 85 K; on the proton donor–acceptor affinity of the primary nitramine (HNNO₂) group

Abstract

The NNO 2 group of the title compound is signi®cantly less twisted with respect to the aromatic ring in comparison to a typical secondary nitramine. The amide nitrogen is trigonally hybridized. The nitramino group is almost planar. The CÐCÐ NÐN torsion angles vary between ca 13 and 42 , whereas the twist along the NÐN bond is much smaller and amounts to between ca 1 and 15 . Those twist angles are governed by a crystal packing and are much larger in the case of crystals of pure N,4-dinitroaniline in comparison to that of its complex with sulfolane. The deviations of the internal angles of the aromatic ring from 120 do not exceed 3 . The presence of the nitro group increases the CÐCÐC valence angle of ca 2.0± 2.6 , whereas an analogous effect associated with the nitramino group is much smaller (ca 0.3±1.3 ), pointing to its weak electron-withdrawing properties. The nitramino group displays no tendency to conjugate with an electron-demanding substituent across the ring. It participates in hydrogen bonding only as a hydrogen-bonding donor. It does not act as a proton acceptor, despite the fact that nitramine rearrangement is catalysed by acids.

Bruguiesulfurol, A New Sulfur Compound fromBruguiera gymnorrhiza

“…The presence of the HMBC and the 1 H-1 H COSY correlations among the protons and carbons of these alkyl groups revealed the moiety of a CH 2 -CH-CH 2 unit in 1. In comparison with the 13 C-NMR data of brugierol (2) and isobrugierol (3) [24], [25], the carbon signal of C-4 in 1 is significantly shifted upfield, which suggested an O = S = O group in 1. A planar structure of 1,1-dioxo-1l 6 ± [1, 2]dithiolan-4-ol was thus proposed for 1.…”

2,4,6-Trimethyl-N-nitroaniline

“…1) is nearly planar, and the sum of the valence angles [358.0 (12) ] around atom N7 indicates trigonal hybridization of the amide N atom. In pyridine derivatives (III) and (IV), these bonds are more than 0.05 A Ê shorter (Zaleski et al, 2001) than in (I). The torsion angle along the NÐN bond is small at 4.4 (11) (averaged) and may result from non-valence interactions.…”

Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging of Tissues via the Formation of Reproducible Matrix Crystals by the Fluorescence-Assisted Spraying Method: A Quantification Approach

“…Moreover, although cocrystallization of the matrix, R6G, and analyte was not confirmed, the addition of O -DNB, not nitrobenzene, clearly improved the homogeneity and fineness of the crystal formation of the sprayed 1,5-DAN matrix (Figure S5) (average crystal diameter of sprayed droplets, 1,5-DAN only: 72 μm, nitrobenzene: 54 μm, and O -DNB: 25 μm). Compounds containing nitro groups could be crystallized in compact crystal structures and sizes by tight and strong N–H···O hydrogen bonds regarding the amino group. − Based on these findings, the optimized concentration of O -DNB (10 mg/mL) in the solution of the 1,5-DAN matrix (10 mg/mL), which exhibited the finest and most homogeneous matrix crystals, was employed for the subsequent experiments. Figure B shows the fluorescence images and intensities of the sprayed R6G.…”