Crystal structures of 2,3-bis-(4-chloro-phen-yl)-1,3-thia-zolidin-4-one and trans-2,3-bis-(4-chloro-phen-yl)-1,3-thia-zolidin-4-one 1-oxide.

In the crystal structures of the title compounds, C15H11Cl2NOS, (1), and C15H11Cl2NO2S, (2), wherein (2) is the oxidized form of (1), the thia-zolidine ring is attached to two chloro-phenyl rings. The chloro-phenyl ring on the 2-carbon atom position points in the same direction as that of the S atom in (1), while in (2), the S atom points in the opposite direction. The O atom on the chiral S atom in (2) is trans to the chloro-phenyl ring on the 2-carbon. The chloro-phenyl ring planes in each structure are close to orthogonal, making dihedral angles of 78.61 (6) and 87.46 (8)° in (1) and (2), respectively. The thia-zolidine ring has a twisted conformation on the S-Cmethine bond in (1), and an envelope conformation with the S atom 0.715 (3) Å out of the plane of other four atoms in (2). In the crystal of (1), mol-ecules are linked by C-H⋯O hydrogen bonds, as well as by slipped parallel π-π inter-actions [inter-centroid distance = 3.840 (3) Å] between inversion-related phenyl rings, forming sheets parallel to (001). In the crystal of (2), mol-ecules are linked via C-H⋯O and C-H⋯Cl hydrogen bonds, forming slabs parallel to (001).