Domain: Inorganic main-group chemistry

Ammonia (NH_3) reacts with sulfur dichloride (SCl_2) to furnish an intermediate A, accompanied by ammonium chloride (NH_4Cl) and elemental sulfur (S). The intermediate A then combines with chlorine (Cl_2) to give B, which in the presence of additional Cl_2 undergoes a reversible transformation to a mixture of C and D; both C and D are sulfur–nitrogen–chlorine species containing S, N, and Cl. The species D decomposes to disulfur dichloride (S_2Cl_2) and dinitrogen (N_2). Identify the molecular species D.

Grading rubric:
criterion: Correctly identifies the cage-like intermediate A as tetrasulfur tetranitride (S_{4}N_{4}).
weight: 10
criterion: Correctly identifies the oxidative addition of chlorine to A yielding the bicyclic intermediate B as S_4N_4Cl_2 (B).
weight: 10
criterion: Correctly interprets the ring transformation of B in excess chlorine as a depolymerization process.
weight: 10
criterion: Correctly identifies the trimeric species C as trithiazyl trichloride (S_{3}N_{3}Cl_{3}).
weight: 10
criterion: Correctly identifies the monomeric species D as thiazyl chloride (NSCl).
weight: 20
criterion: Correctly characterizes the relationship between C and D as a trimer-monomer equilibrium.
weight: 10
criterion: Correctly deduces the identity of D based on its specific thermal decomposition into S_{2}Cl_{2} and N_2.
weight: 10
criterion: Correctly provides the molecular formula of the final target species D as NSCl.
weight: 20

Answer:
thiazyl chloride (NSCl)