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

What is it about?

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, 2C11H12N3S·C6N8. 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 [pi]-stacking is indicated by a CT band around 550 cm-1 in the single-crystal absorption spectrum.

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