Poly[bis­(μ-5-iodo­isophthal­ato)(methanol)dilead(II)] exhibiting a novel centrosymmetric rhombus-shaped I₄ unit

The asymmetric unit of the title compound, [Pb₂(C₈H₃IO₄)₂(CH₄O)]_n, contains two Pb^II atoms, two 5-iodo­isophthalate (5-IIP²⁻) ligands and one coordinated methanol mol­ecule. One Pb atom is eight-coordinated, surrounded by seven carboxyl­ate O atoms from five 5-IIP²⁻ ligands and one O atom from the terminal methanol ligand. The other Pb atom is seven-coordinated in a hemidirected geometry, surrounded by seven carboxyl­ate O atoms from five 5-IIP²⁻ ligands. Both Pb atoms are connected by carboxyl­ate groups to form a one-di­men­sional infinite rod along the a axis; neighbouring rods are further linked by the aromatic rings of 5-IIP²⁻ to generate the final three-dimensional structure with channels in the a direction. An O—H...O hydrogen bond between the methanol ligand and one of the carboxyl­ate groups of a 5-IIP²⁻ ligand stablizes the three-dimensional framework. Inter­estingly, a centrosymmetric rhombus-shaped I₄ unit is formed by four 5-IIP²⁻ ligands, with I...I distances of 3.8841 (8) and 3.9204 (8) Å.