Poly[tetra-aqua-μ(3)-benzene-1,2-di-carboxyl-ato-μ(3)-bromido-penta-μ(2)-bromido-octa-μ(3)-isonicotinato-hepta-copper(I)trilanthanum(III)].

A new lanthanum(III)-copper(I) heterometallic coordination polymer, Cu(7)La(3)Br(6)(C(6)H(4)NO(2))(8)(C(8)H(4)O(4))(H(2)O)(4), has been prepared by a hydro-thermal method. Of the three La atoms in the asymmetric unit, two are eight-coordinate with bicapped trigonal-prismatic configurations; the third is nine-coordinated and has a tricapped trigonal-prismatic coordination geometry. Of the seven Cu atoms, two are two-coordinate with CuBrN and CuN(2) ligand sets, three have trigonal configurations, viz. CuBrN(2), CuBr(2)N and CuBr(3), while the remaining two adopt distorted tetra-hedral CuBr(3)N geometries. In the crystal structure, adjacent La centers are linked by isonicotinate (IN(-)) and benzene-1,2-dicarboxyl-ate ligands to form a two-dimensional La-carboxyl-ate layer in the ab plane. These layers are further inter-connected with each other by bridging [Cu(IN)(2)] motifs, leading to an unusual three-dimensional heterometallic Cu-halide-lanthanide-organic framework, with the inorganic Cu(6)Br(6) chains located in the resulting channels. Two Cu atoms are disordered over two positions, both with site occupancy factors of 0.80 and 0.20. O-H⋯O hydrogen bonding between water molecules and carboxylate O atoms helps to consolidate the crystal packing.