Polymeric dihydroxydiphthalatotricobalt(II)

In the crystal structure of di­hydroxy­diphthalatotricobalt(II), Co₃(C₈H₄O₄)₂(OH)₂]_n, two of the four independent Co atoms lie at special positions of site symmetry 2. The hydroxy groups link three Co atoms to form a pyramidal Co₃O unit, and adjacent Co₃O units are linked through the Co base atoms into a honeycomb layer motif. Each of the phthalate dianions uses the O atoms of one carboxyl group to bind to three Co atoms, the bonding mode giving rise to six‐coordinate Co atoms.