Crystal structure of di-μ-aqua-μ-(pyrazine N , N ′-dioxide)-κ 2 O : O -bis(diaquasodium) tetraphenylborate dihydrate pyrazine N , N ′-dioxide monosolvate

The search for novel lanthanide coordination networks using pyrazine N,N′ -dioxide (pzdo, C 4 H 4 N 2 O 2 ) as a structure-directing unit, led to the synthesis and the structure determination of the title compound, [Na 2 (C 4 H 4 N 2 O 2 )(H 2 O) 6 ][B(C 6 H 5 ) 4 ] 2 ·C 4 H 4 N 2 O 2 ·2H 2 O. The crystal structure is comprised of discrete [{Na(H 2 O) 2 } 2 (μ-H 2 O) 2 (μ-pzdo)] 2+ cations and tetraphenylborate anions, as well as pzdo and H 2 O solvent molecules. 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 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.