Hexaaquacopper(II) bis(tetrafluoridoborate)–pyrazine 1,4-dioxide (1/3)

Abstract

The crystal structure of the title compound, [Cu(H2O)6](BF4)2·3C4H4N2O2, comprises discrete [Cu(H2O)6]2+ cations and BF4− anions along with three equivalents of pyrazine 1,4-dioxide (pzdo). The hexaaquacopper(II) ion and all three pzdo molecules lie about crystallographic inversion centers. The lattice is supported by an extensive hydrogen-bonding network. O—H...O hydrogen bonding between the [Cu(H2O)6]2+ and pzdo units creates a pseudo-hexagonal lattice parallel to the bc plane. The BF4− anions lie in the voids of that lattice, held in place by O—H...F hydrogen bonds, and also generate BF4−–pzdo–BF4−–pzdo stacks via short F...N contacts [2.866 (3)–3.283 (4) Å].