Molecular and crystal structures of 2,4,6-trinitro-N-methyl-N-nitroaniline

The structure of single crystals of 2,4,6-trinitro-N-methyl-N-nitroaniline C₇H₅N₅O₈ (I) is determined by X-ray diffraction analysis. The unit cell parameters are a = 14.137(3) Å, b = 10.621(2) Å, c = 7.376(2) Å, γ = 95.19 (5)°, space group P2₁/b, and Z = 4. The structure is solved by the direct method and refined in the anisotropic approximation to R = 0.051 for 1917 reflections with I > 2σ(I). All hydrogen atoms are located and refined in the isotropic approximation. The carbon skeleton of the aromatic nucleus of the molecule tends to adopt the C(2),C(5)-boat conformation. The angle of rotation of the planar NNO₂ group with respect to the plane of the six-membered ring is 123.1(2)°. The NO₂groups that are bonded to the aromatic nucleus of the molecule are also rotated relative to this plane.     

High-resolution solid-state NMR spectroscopy as a tool for investigation of enantioselective inclusion complexation

In this paper, we showed the application of solid state-NMR (SS NMR) spectroscopy in structural studies of chiral compounds employing sample of (E)-1-diphenylphosphinoylpent-3-en-2-ol 1 as a model compound. Racemate of 1 was fully characterized by NMR techniques (both in liquid and solid phase) and X-ray crystallography. Theoretical calculations employing the GIAO approach were used to explain the influence of hydrogen bonding on 31P NMR shielding parameter in racemate. Enantioselective inclusion complexation (EIC) method with TADDOL as host molecule was applied to separate of enantiomers. The formation of host-guest complex and decomplexation procedure was monitored by means of the SS NMR. The liquid-state NMR, due to similarity of 13C and 31P spectral parameters was not able to distinguish racemate from enantiomer. In the solid phase, owing to distinction of hydrogen bonding and molecular packing in the crystal lattice, racemate and enantiomers were easy recognized by NMR spectroscopy.