catena-Poly[[tetra-μ(3)-isonicotinato-μ(3)-oxalato-μ(2)-oxalato-disamarium(III)disilver(I)] dihydrate]

In the title compound, {[AgSm(C(6)H(4)NO(2))(2)(C(2)O(4))]·H(2)O}(n), the asymmetric unit contains one Sm(III) ion, one Ag(I) ion, two unique isonicotinate (ina) ligands, two half oxalate (ox) ligands (one on an inversion centre, the other on a twofold axis) and one uncoordinated water mol­ecule. The central Sm(III) ion is nine-coordinated by four O-donor atoms from separate bidentate bridging ox ligands and five O-donor atoms from the two ina ligands (both bidentate) and a symmetry-related ina ligand [Sm—O = 2.389 (4)–2.791 (4) Å], giving a distorted monocapped square anti­prismatic geometry. The Ag(I) ion is three-coordinated in a T-shaped geometry involving two ina N-donor atoms [Ag—N = 2.181 (6) and 2.185 (5) Å] and a bridging oxalate O-donor atom [Ag—O = 2.620 (4) Å]. The three-dimensional heterometallic Sm—Ag coordination polymer, having a unique (3,4,6)-connected five-nodal net topology, is constructed from two-dimensional samarium–oxalate layers and pillared Ag(ina)(2) subunits. Inter­molecular water–carboxyl­ate O—H⋯O hydrogen-bonding inter­actions are also present.