Find in Library

The reaction of copper(II) nitrate hexahydrate with pyridine-2,6-dicarboxylic acid (pydcH2) and 2,4,6-triamino-1,3,5-triazine (melamine) in aqueous solution in a 1:2:2 molar ratio gave the title compound, (H5O2)(C3H7N6)3[Cu(C7H3NO4)2]2·C7H5NO4·6H2O. The hydroxonium hydrate (H5O2)+, also known as the Zundel cation, resides on a twofold rotation axis. The O—H distance is 1.274 (14) Å, the O...O distance is 2.518 (5) Å, and the O—H—O angle is 162 (8)°. One of the melamine H+ cations, the uncoordinated pydcH2, and two water molecules also reside on crystallographic twofold axes. The CuII atom has a tetragonally distorted octahedral coordination environment. The structure features extensive hydrogen bonding, with 21 distinct interactions. There is also a centrosymmetric C=O...π interaction with an O...centroid distance of 3.288 (3) Å. The structure is similar to a mixed-valence manganese(II/III) structure but shows interesting differences in the metal-atom coordination. One of the water molecules is equally disordered with respect to a twofold axis.