Crystal structures and Hirshfeld surfaces of two 1,3-benzoxathiol-2-one derivatives

The crystal structures of 6-meth­oxy-1,3-benzoxa­thiol-2-one, C9H8O3S, (I), and 2-oxo-1,3-benzoxa­thiol-6-yl acetate, C9H6O4S, (II), are described. Compound (I) is almost planar (r.m.s. deviation for the non-H atoms = 0.011 A), whereas (II) shows a substantial twist between the fused-ring system and the acetate substituent [dihedral angle = 74.42 (3)°]. For both structures, the bond distances in the heterocyclic ring suggest that little if any conjugation occurs. In the crystal of (I), C—H⋯O hydrogen bonds link the mol­ecules into [1-11] chains incorporating alternating R22(8) and R22(12) inversion dimers. The extended structure of (II) features C(7) [201] chains linked by C—H⋯O hydrogen bonds, with further C—H⋯O bonds and weak π–π stacking inter­actions connecting the chains into a three-dimensional network. Hirshfeld fingerprint analyses for (I) and (II) are presented and discussed.