Crystal structures of 2-[5-nitrothien-2-yl)- CH=N–NR–CO(CH2)n]thiophene compounds (R = H or Me; n = 0 or 1)

Abstract

AbstractThe crystal structures of four acylhydrazonyl derivatives of thiophene, 2-(ArCH=N–NHCO)- thiophene, (1a),2-(ArCH=N–NMeCO)-thiophene, (2a), 2-(ArCH=N–NHCOCH2)-thiophene, (3a) and 2-(ArCH=N–NMeCOCH2)-thiophene, (4a) [in each case Ar=5-nitrothien-2-yl] are reported. The molecular conformations of1aand2aare near planar, while those of3aand4aexhibit bends at the methylene carbon. Methylations at the hydrazonyl groups in1aand3a, to give2aand4a,do not result in any significant changes in the molecular conformations. Each of the four molecular conformations possesses aZC(O)NR/E(C=N)arrangement about the C(O)–NR–N=C(H, aryl) fragment (R=H or Me). The dominant intermolecular interactions in1aand3aare N–H···O(carbonyl) hydrogen bonds, with other intermolecular interactions being weaker interactions: C–H···O and N–O···π in1aand C–H···X (X=O, S, π) and π–π interactions in3a. In theN-methylated compounds, the intermolecular interactions are restricted to weaker C–H···O hydrogen bonds in2aand C–H···X (X=O or π) interactions in4a.