O. F. Vázquez-Vuelvas, D. Morales‐Morales, J. M. Germán-Acacio
Jan 14, 2011
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Journal
Journal of Chemical Crystallography
Abstract
Two new 1,3,3-trimethyl-2-methylene-2,3-dyhidro-1H-indole derivatives, (E)-2,3-dihydro-2-(4-cyanophenylacylidene)-1,3,3-trimethyl-1H-indole, (I), and (E)-2,3-dihydro-2-(4-chlorophenylacylidene)-1,3,3-trimethyl-1H-indole, (II), have been synthesized and their crystal structure determined by single crystal X-ray diffraction. (I), C20H18N2O, crystallizes in a monoclinic space group, P21/c, with unit cell parameters a = 9.882 (3), b = 15.614(4), c = 11.181(3) Å, β = 106.691(4)°, Z = 4. (II), C19H18Cl N O, crystallizes in a monoclinic space group, P21/n, with unit cell parameters a = 14.6722(19), b = 7.2597(9), c = 16.304(2) Å, β = 111.249 (2)°, Z = 4. The molecules consist of a enaminoketone group formed by a Fischer base 1,3,3-trimethyl-2-methylene-2,3-dihydro-1H-indole bonded, at the exocyclic electron-rich β-carbon atom of the indole moiety, with the benzoyl chloride derivatives substituted at para-positions with cyano and chloro groups. The molecules adopt a s-cis conformation with respect to the C=O bond towards the C=C bond, and a E configuration about the latter indole exocyclic alkene C–C bond. Intermolecular arrangement of the crystals show, for (I) an antiparallel stacking mode favored by the formation of weak C–H···π interactions involving the phenyl ring attached to the carbonyl group and the phenyl of the indole fragment in a head-to-tail mode, whereas, (II) present an weak C–H···Hal interaction.Index AbstractSynthesis and characterization by X-ray diffraction of the molecules (E)-2,3-dihydro-2-(R-phenylacylidene)-1,3,3-trimethyl-1H-indole [R = 4-CN (I), 4-Cl(II)]. The crystal structures of (E)-2,3-dihydro-2-(R-phenylacylidene)-1,3,3-trimethyl-1H-indole (R = 4-CN, 4-Cl), gets stabilized by weak intra and intermolecular C–H···O type hydrogen bonds. The crystals present a stacking mode favored in (I), by the formation of weak C–H···π interaction involving the phenyl attached to the carbonyl group and the phenyl of the indole fragment, whereas, (II) presents a weak C–H···Hal interaction.