Crystal structure and polarized vibrational spectra of 2‐bromo‐4‐nitropyridine N‐oxide single crystal

Abstract

2-Bromo-4-nitropyridine N-oxide is orthorhombic, space group Pbca, with eight molecules per unit cell of dimensions a = 5.979.1/, b = 9.899.1/, c = 23.249.5/Å. The Br ion is nearly coplanar with the pyridine ring, while the two oxygen atoms of the nitro group are displaced above and below the ring by (−0.214Å) and (+0.053Å). The hydrogen bond of the type C -H· · ·O links the molecules into pairs around centers of symmetry. These dimers, arranged into layers related by glide planes, are held together solely by contacts of the van der Waals type. The polarized Fourier transform IR and Raman spectra, measured in the regions 30-3500 and 80-3500 cm −1 , respectively, are correlated with x-ray structural data. Comparison of the spectrum of the dissolved sample with the spectra obtained from the polycrystalline sample and single crystals shows the attractive character of the intermolecular C -H· · ·O contacts for these molecules. The temperature-dependent IR spectra suggest the presence of orientational disorder at higher temperatures.

Ferroelectric phase transition in hydrogen-bonded 2-aminopyridine phosphate (NC4H4NH2) H3PO4

“…The C-C and C-N bond lengths range from 1.350(2) to 1.412(2) Å and 1.330(2) to 1.361(2) Å, respectively. The molecular geometry is similar to that observed in related pyridine containing compounds [14,15]. The N atom of the amino group with its hydrogen atoms lies in the plane of the ring.…”

Vibrational spectra, X‐ray and molecular structure of 1H‐ and 3H‐imidazo[4,5‐b]pyridine and their methyl derivatives: DFT quantum chemical calculations

“…Other interatomic separations and valence angles are comparable with the values published for similar compounds. 54,55 Molecular structure of the 1HIP, 3HIP and 5MIP, 6MIP…”

Vibrational spectra, crystal structure, DFT quantum chemical calculations and conformation of the hydrazo – bond in 6-methyl-3-nitro-2-(2-phenylhydrazinyl)pyridine

“…1. The internal variations between the bond lengths are considerable but do not follow any regular pattern (Table 1) [36][37][38]. The phenyl moiety of the molecule is planar.…”