Dimeric structure and hydrogen bonds in 2-N-ethylamino-5-metyl-4-nitro-pyridine studied by XRD, IR and Raman methods and DFT calculations

The molecular structure of 2-N-ethylamino-5-methyl-4-nitropyridine (EN5MP) and its vibrational spectra have been analyzed in terms of quantum chemical DFT calculations (B3LYP/6-311++G(d,p) approaches) and related to the XRD data. The EN5MP crystal is triclinic and centrosymmetric and its unit-cell is built by asymmetric units consisting of two parallelly arranged formula units, 2[C8H11N3O2], of different conformations. In each of the two subunits the methyl carbons and N-atoms of the nitro group are coplanar with the pyridine ring, but the O-atoms are inclined from this plane in the opposite directions. Dimers are linked by intermolecular NH⋯N hydrogen bonds system. Properties of the NAH⋯NP interactions between the hydrogen atom of the pyridine ring NP and the hydrogen atom of the amino group NA have been characterized. Additionally the crystal structure is stabilized by a set of weak intermolecular CH⋯O interactions.