Crystal structures of two hydrazinecarbothioamide derivatives: ( E )- N -ethyl-2-[(4-oxo-4 H -chromen-3-yl)methylidene]hydrazinecarbothioamide hemihydrate and ( E )-2-[(4-chloro-2 H -chromen-3-yl)methylidene]- N -phenylhydrazinecarbothioamide

The title compounds, C 13 H 13 N 3 O 2 S·0.5H 2 O, (I), and C 17 H 14 ClN 3 OS, (II), are hydrazinecarbothioamide derivatives. Compound (I) crystallizes with two independent molecules ( A and B ) and a water molecule of crystallization in the asymmetric unit. The chromene moiety is essentially planar in molecules A and B , with maximum deviations of 0.028 (3) and 0.016 (3) Å, respectively, for the carbonyl C atoms. In (II), the pyran ring of the chromene moiety adopts a screw-boat conformation and the phenyl ring is inclined by 61.18 (9)° to its mean plane. In the crystal of (I), bifurcated N—H...O and C—H...O hydrogen bonds link the two independent molecules forming A – B dimers with two R 2 1 (6) ring motifs, and R 2 2 (10) and R 2 2 (14) ring motifs. In addition to these, the water molecule forms tetrafurcated hydrogen bonds which alternately generate R 4 4 (12) and R 6 6 (22) graph-set ring motifs. There are also π–π [inter-centroid distances = 3.5648 (14) and 3.6825 (15) Å] interactions present, leading to the formation of columns along the c -axis direction. In the crystal of (II), molecules are linked by pairs of N—H...S hydrogen bonds, forming inversion dimers with an R 2 2 (8) ring motif. The dimers are linked by C—H...π interactions, forming ribbons lying parallel to (210).