Monoclinic modification of bis­(μ(2)-pyridine-2,6-dicarboxyl­ato)-κ(4) O (2),N,O (6):O (6);κ(4) O (2):O (2),N,O (6)-bis­[aqua­dibutyl­tin(IV)]

The Sn(IV) atom in the centrosymmetric dinuclear title compound, [Sn(2)(C(4)H(9))(4)(C(7)H(3)NO(4))(2)(H(2)O)(2)], exists in a trans-C(2)SnNO(4) penta­gonal–bipyramidal geometry. There are two half-mol­ecules in the asymmetric unit that are completed by inversion symmetry. The crystal studied was a non-merohedral twin with a ratio of 47.3 (1)% for the minor twin component. Bond dimensions are similar to those found in the tetra­gonal polymorph [Huber et al. (1989 ▶). Acta Cryst. C45, 51–54]. O—H⋯O hydrogen-bonding interactions stabilize the crystal packing.