Molecular packing modes. Part I. Crystal and molecular structures of p-chlorocinnamide

Abstract

The crystal structure of p-chlorocinnamide, representing a primary-amide packing type not hitherto reported, has been solved from three-dimensional precession data (Mo-K_α) by means of SEARCH and refined to R 0·06 and R′(the weighted value of R) 0·015. Bond lengths and angles between the heavier atoms have been determined with an estimated standard deivation of 0·005 Å and 0·3°. The molecule is not planar, the dihedral angles between the ClC₆H₄, CH:CH, and CONH₂ groups being 14·2 and 7·1°.

The crystal structure consists of screw-axis related centrosymmetric amide pairs located at (0,0,0) and (0,½,½) linked by a second set of N–H ⋯ O bonds.