Poly[diaqua­(μ₄-carboxyl­atomethyl­phospho­nato)(μ₄-carb­oxy­methyl­phospho­nato)penta­deca­methyl­penta­tin(IV)]

The central Sn^IV atom of the penta­nuclear title complex, {[Sn(CH₃)₃]₃O₂C(CH₂)PO₃[Sn(CH₃)₃(H₂O)]₂HO₂C(CH₂)PO₃}, is located on a twofold rotation axis; due to symmetry, the H atom of the carboxyl group of the anion is disordered with a site occupancy of 0.5. The central Sn^IV atom is bonded to three methyl groups (one of which is disordered about the twofold rotation axis) and is symmetrically trans coordinated by two phospho­nate groups with Sn—O = 2.2665 (12) Å while the other SnMe₃ residues are asymmetrically trans coordinated with Sn—O = 2.1587 (12) and 2.3756 (13) Å for one residue and Sn—O = 2.1522 (12) and 2.4335 (12) Å for the other; the Sn–O distances involving two O atoms trans to carboxyl­ate are longer than those trans to phospho­nate groups. The Sn—C distances lie in a very narrow range [2.112 (2)–2.133 (3) Å]. The oxyanion behaves as a tetra-coordinating ligand. The bridging mode of the latter leads to the formation of layers parallel to (001) that are inter­connected by O—H...O and C—H...O hydrogen bonds.