Enantiopure (S)-butan-2-yl N-(4-x-phenyl)thiocarbamates, x = NO2, OCH3, F, and Cl

Abstract

The structures of (S)-butan-2-yl N-(4-nitrophenyl)thiocarbamate, C11H14N2O3S, (I), (S)-butan-2-yl N-(4-methoxyphenyl)thiocarbamate, C12H17NO2S, (II), (S)-butan-2-yl N-(4-fluorophenyl)thiocarbamate, C11H14FNOS, (III), and (S)-butan-2-yl N-(4-chlorophenyl)thiocarbamate, C11H14ClNOS, (IV), all at 100 K, have monoclinic (P21) symmetry with two independent molecules in the asymmetric unit. The Flack absolute structure parameters in all cases confirm the absence of inversion symmetry. The structures display N—H...S hydrogen bonds, resulting in R 2 2(8) hydrogen-bonded ring synthons connecting the two independent molecules. Despite the ring synthon, the packing follows two distinct patterns, with (I) and (IV) `pancaking' along the b-axis direction, while the other two `sandwich' in layers perpendicular to the b axis. Crystal morphologies were determined theoretically via the BFDH (Bravais, Friedel, Donnay–Harker) model and agree qualitatively with the experimentally indexed results. One of the butyl substituent of (II) exhibits structural disorder.