Enanti-opure (S)-butan-2-yl N-(4-x-phen-yl)thio-carbamates, x = NO2, OCH3, F, and Cl.

The structures of (S)-butan-2-yl N-(4-nitro-phen-yl)thio-carbamate, C11H14N2O3S, (I), (S)-butan-2-yl N-(4-meth-oxy-phen-yl)thio-carbamate, C12H17NO2S, (II), (S)-butan-2-yl N-(4-fluoro-phen-yl)thio-carbamate, C11H14FNOS, (III), and (S)-butan-2-yl N-(4-chloro-phen-yl)thio-carbamate, C11H14ClNOS, (IV), all at 100 K, have monoclinic (P21) symmetry with two independent mol-ecules 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 mol-ecules. 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.