Crystal structure of di-μ-aqua-μ-(pyrazine N,N'-dioxide)-κ(2) O:O-bis-(di-aqua-sodium) tetra-phenyl-borate dihydrate pyrazine N,N'-dioxide monosolvate

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 tetra-phenyl-borate anions, as well as pzdo and H2O solvent mol-ecules. The dinuclear cation is located about a twofold rotation axis, and the symmetry-related Na(I) 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 mol-ecules (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 inter-actions link the anion and solvent water mol-ecules 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 tetra-phenyl-borate anion.