Acta Crystallographica Section E (Mar 2014)
The title compound, [Cu(C5H3N6)2(H2O)2]·2C5H3N3, is a 1:2 co-crystal between the mononuclear complex diaquabis[5-(pyrazin-2-yl)tetrazolato]copper(II) and the reagent pyrazine-2-carbonitrile which was used in the synthesis. The CuII atom is located on an inversion centre and has a distorted octahedral [4 + 2]-coordination environment formed by four N atoms of two chelating bidentate 5-(pyrazin-2-yl)tetrazolate ligands at shorter distances and two water O atoms at longer distances. The CuII complex molecules are held together by O—H...N hydrogen bonds and π–π stacking interactions [centroid–centroid distance 3.6139 (8) Å], forming layers parallel to (100). These layers alternate with layers of pyrazine-2-carbonitrile molecules and both are held together via C—H...N hydrogen bonds and further π–π stacking interactions.