Abstract
The syntheses and crystal structures of two isomers of phenyl iso-thia-zolyl oxa-thia-zolone, C11H6N2O2S2, are described [systematic names: 5-(3-phenyl-iso-thia-zol-5-yl)-1,3,4-oxa-thia-zol-2-one, (I), and 5-(3-phenyl-iso-thia-zol-4-yl)-1,3,4-oxa-thia-zol-2-one, (II)]. There are two almost planar (r.m.s. deviations = 0.032 and 0.063 Å) mol-ecules of isomer (I) in the asymmetric unit, which form centrosymmetric tetra-mers linked by strong S⋯N [3.072 (2) Å] and S⋯O contacts [3.089 (1) Å]. The tetra-mers are π-stacked parallel to the a-axis direction. The single mol-ecule in the asymmetric unit of isomer (II) is twisted into a non-planar conformation by steric repulsion [dihedral angles between the central iso-thia-zolyl ring and the pendant oxa-thia-zolone and phenyl rings are 13.27 (6) and 61.18 (7)°, respectively], which disrupts the π-conjugation between the heteroaromatic iso-thia-zoloyl ring and the non-aromatic oxa-thia-zolone heterocycle. In the crystal of isomer (II), the strong S⋯O [3.020 (1) Å] and S⋯C contacts [3.299 (2) Å] and the non-planar structure of the mol-ecule lead to a form of π-stacking not observed in isomer (I) or other oxa-thia-zolone derivatives.
Highlights
The syntheses and crystal structures of two isomers of phenyl isothiazolyl oxathiazolone, C11H6N2O2S2, are described [systematic names: 5-(3-phenylisothiazol-5-yl)-1,3,4-oxathiazol-2-one, (I), and 5-(3-phenylisothiazol-4-yl)-1,3,4oxathiazol-2-one, (II)]
S C contacts [3.299 (2) Å] and the non-planar structure of the molecule lead to a form of -stacking not observed in isomer (I) or other oxathiazolone derivatives
The isothiazolyl ring is recognised as a heteroaromatic ring with extensive -delocalization within the ring leading to almost planar heterocycles
Summary
Compounds containing the isothiazolyl moiety are well known in organic and pharmacological research, with extensive reviews on the synthesis and chemistry of the ring (AbdelSattar & Elgazwy, 2003) and the medicinal and industrial uses of compounds containing the isothiazolyl heterocycle (Kaberdin & Potkin 2002). The extent of -delocalization within the oxathiazolone ring and to the substituent group and the effect on the structure and chemical properties have been discussed spectroscopically (Markgraf et al, 2007) and structurally (Krayushkin et al., 2010a,b). Our interest in this system was prompted by the possibility that catenated systems of isothiazolone heterocycles may have useful electronic properties as the number of systems is increased. The bond lengths of the endocyclic bonds in the isothiazolyl moieties in (I) and (II) are not significantly ( > 3) different from the
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