A one-dimensional copper(II) phenylenediphosphonate: Catenapoly[[(1,10- phenanthroline-κ² N,N′)copper(II)]-μ₃-[m- phenylenediphosphonato-κ³ O:O′:O″]]

The title compound, [Cu(1,3-HO₃PC₆H ₄PO₃H)(C₁₂H₈N₂)] _n, is a coordination polymer of the metal-diphospho-nate family. The chain structure is constructed from 4+1 square-py-rami-dally coordinated copper(II) atoms bonded to chelating phenanthroline (phen) ligands and linked through 1,3-phenyldihydrogendiphospho-nate ligands. The basal plane of the Cu(II) site is defined by the phen nitro-gen donors and phospho-nate oxygen atoms from two diphospho-nate ligands, while the apical position is occupied by an oxygen donor from a third diphospho-nate ligand. The chains propagate along the a-axis direction. Inversion-related phen groups engage in π-π stacking with a mean distance of 3.376 (2) Å between the ring planes. O - H⋯O hydrogen-bonding interactions between the protonated {P - OH} groups of one chain and the {P=O} groups of adjacent chains stabilize the crystal packing.