Crystal Structure and Solid-State Packing of 4-Chloro-5 H-1,2,3-dithiazol-5-one and 4-Chloro-5 H-1,2,3-dithiazole-5-thione

Abstract

The crystal structure and solid-state packing of 4-chloro-5H-1,2,3-dithiazol-5-one and two polymorphs of 4-chloro-5H-1,2,3-dithiazole-5-thione were analyzed and compared to structural data of similar systems. These five-membered S,N-rich heterocycles are planar with considerable bond localization. All three structures demonstrate tight solid-state packing without voids which is attributed to a rich network of short intermolecular electrostatic contacts. These include S^δ+…N^δ-, S^δ+…O^δ-, S^δ+…Cl^δ- and S^δ+…S^δ- interactions that are well within the sum of their van der Waals radii (∑_VDW). B3LYP, BLYP, M06, mPW1PW, PBE and MP2 were employed to calculate their intramolecular geometrical parameters, the Fukui condensed functions to probe their reactivity, the bond order, Bird Index and NICS(1) to establish their aromaticity.

Keywords: 1,2,3-dithiazol-5-one; 1,2,3-dithiazole-5-thione; 1,2,3-dithiazoles; Appel’s salt; dithiazines; thiazoles.

Scheme 1

Structure of Appel’s salt 1; the preparation reaction of neutral 4-chloro-5H-1,2,3-dithiazoles 2a–d; IUPAC numbering of the ring system [3,4,5,6].

Figure 1

Intermolecular short contacts (Å) expanded for the central dithiazolone 2b in the asymmetric unit cell.

Figure 2

Intermolecular short contacts (Å) expanded for the central dithiazolethione 2c–α in the asymmetric unit cell.

Figure 3

Intermolecular short contacts (Å) for the three supramolecular triangles of dithiazolethione 2c–β formed by the six molecules in the asymmetric unit cell.

Figure 4

HOMO and LUMO orbitals calculated at the B3LYP/def2-TZVPD level of theory along with their energies (eV) and the ε_HL: HOMO-LUMO gap (eV) for Appel’s salt 1, dithiazolone 2b and dithiazolethione 2c.