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

The title compounds, C13H13N3O2S center dot 0.5H(2)O, (I), and C17H14ClN3OS, (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) angstrom, 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)degrees to its mean plane. In the crystal of (I), bifurcated N-H center dot center dot center dot O and C-H center dot center dot center dot 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 pi-pi [inter-centroid distances = 3.5648 (14) and 3.6825 (15) angstrom] 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 center dot center dot center dot S hydrogen bonds, forming inversion dimers with an R-2(2)(8) ring motif. The dimers are linked by C-H center dot center dot center dot pi interactions, forming ribbons lying parallel to (210).