Crystal structure of the charge-transfer complex 2-(1,2,3,4-tetra­hydro­naph­thal­en-1-yl­idene)hydrazinecarbo­thio­amide–pyrazine-2,3,5,6-tetra­carbo­nitrile (2/1)

The reaction of 2-(1,2,3,4-tetra­hydro­napthalen-1-yl­idene)hydrazinecarbo­thio­amide (TTSC) with pyrazine-2,3,5,6-tetra­carbo­nitrile (tetra­cyano­pyrazine, TCNP) yields the title 2:1 charge-transfer adduct, 2C(11)H(12)N(3)S·C(6)N(8). The complete TCNP mol­ecule is generated by a crystallographic inversion centre and the non-aromatic ring in the TTSC mol­ecule adopts an envelope conformation with a methyl­ene C atom as the flap. In the crystal, the thio­semicarbazone mol­ecules are connected through inversion-related pairs of N—H⋯S inter­actions, building a polymeric chain along the b-axis direction. The TCNP mol­ecules are embedded in the structure, forming TTSC–TCNP–TTSC stacks with the aromatic rings of TTSC and the mol­ecular plane of TCNP in a parallel arrangement [centroid–centroid distance = 3.5558 (14) Å]. Charge-transfer (CT) via π-stacking is indicated by a CT band around 550 cm(−1) in the single-crystal absorption spectrum.