Poly[tetra­aqua-μ(3)-benzene-1,2-di­carboxyl­ato-μ(3)-bromido-penta-μ(2)-bromido-octa-μ(3)-isonicotinato-hepta­copper(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)](n), has been prepared by a hydro­thermal 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 tetra­hedral CuBr(3)N geometries. In the crystal structure, adjacent La centers are linked by isonicotinate (IN(−)) and benzene-1,2-dicarboxyl­ate ligands to form a two-dimensional La–carboxyl­ate layer in the ab plane. These layers are further inter­connected 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)](n) 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.