| Summary: | The search for novel lanthanide coordination networks using pyrazine N,N′-dioxide (pzdo, C4H4N2O2) as a structure-directing unit, led to the synthesis and the structure determination of the title compound, [Na2(C4H4N2O2)(H2O)6][B(C6H5)4]2·C4H4N2O2·2H2O. The crystal structure is comprised of discrete [{Na(H2O)2}2(μ-H2O)2(μ-pzdo)]2+ cations and tetraphenylborate anions, as well as pzdo and H2O solvent molecules. The dinuclear cation is located about a twofold rotation axis, and the symmetry-related NaI atoms display a distorted square-pyramidal coordination sphere defined by two O atoms of terminal water ligands, two O atoms of bridging water ligands and one O atom of a bridging pzdo ligand. In the crystal, O—H...O hydrogen bonds link the dinuclear cation and solvent pzdo molecules (point-group symmetry -1) into rectangular grid-like layers parallel to the bc plane. Additional C—H...O, O—H...O, C—H...π and O—H...π interactions link the anion and solvent water molecules to the layers. The layers are further linked into a three-dimensional network through a combination of C—H...π and O—H...π hydrogen bonds involving the tetraphenylborate anion.
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