Crystal structure of the charge-transfer complex 2-(1,2,3,4-tetra-hydro-naph-thal-en-1-yl-idene)hydrazinecarbo-thio-amide-pyrazine-2,3,5,6-tetra-carbo-nitrile (2/1).

The reaction of 2-(1,2,3,4-tetra-hydro-napthalen-1-yl-idene)hydrazinecarbo-thio-amide (TTSC) with pyrazine-2,3,5,6-tetra-carbo-nitrile (tetra-cyano-pyrazine, TCNP) yields the title 2:1 charge-transfer adduct, 2C11H12N3S·C6N8. The complete TCNP mol-ecule is generated by a crystallographic inversion centre and the non-aromatic ring in the TTSC mol-ecule adopts an envelope conformation with a methyl-ene C atom as the flap. In the crystal, the thio-semicarbazone mol-ecules are connected through inversion-related pairs of N-H⋯S inter-actions, building a polymeric chain along the b-axis direction. The TCNP mol-ecules are embedded in the structure, forming TTSC-TCNP-TTSC stacks with the aromatic rings of TTSC and the mol-ecular 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.