Ethyl 3-(6-phenyl-4λ4-1,2-dithiolo[1,5-b][1,2,4]dithiazol-2-yl)propanoate

The title compound, C15H15NO2S3, exists in a bicyclic form, with resonance contributions from two monocyclic forms, each without a second S—S bond. The trithiapentalene heterocyclic ring system is planar, with a mean deviation of 0.014 (2) Å from the mean plane, and is inclined to the plane of the attached phenyl ring at an angle of 17.24 (7)°.

PJS thanks the Royal Society of New Zealand for the award of a James Cook Research Fellowship.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: GA2023).
The whole molecule is remarkably close to being planar with both substituents lying in the same plane as the trithiaazapentalene ring system. This bicyclic system is planar [mean deviation = 0.014 (3) Å] and the attached phenyl ring is inclined to this plane at an angle of 17.4 (1) °. Inspection of the packing shows that there are short intermolecular contacts [3.491 (1) Å] between sulfur atoms of molecules related by a crystallographic centre of inversion, as well as other weak C-H···O and C-H···π interactions.

Experimental
The title compound was prepared as previously described (Marković et al., 2004).

Refinement
All H atoms were introduced in calculated positions as riding atoms, with U iso (H) = 1.5U eq (C) for the methyl group and U iso (H) = 1.2U eq (C) for other carbons. Fig. 1. The molecular structure of (1), showing displacement ellipsoids at the 50% probability level.  Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.