Poly[[μ(2)-aqua-tetraaquahexakis(μ(4)-naph-thalene-2,6-dicarboxylato)tetra-holmium(III)] 1.75-hydrate]

In the title compound, {[Ho(4)(C(12)H(6)O(4))(6)(H(2)O)(5)]·1.75H(2)O}(n), which is isostructural with its Tb(3+)- and Eu(3+)-containing analogues, there are four crystallographically independent Ho(3+) centres, each exhibiting a highly distorted HoO(8) bicapped trigonal-prismatic coordination environment. Adjacent polyhedra are inter-connected via the carboxyl-ate groups and one μ(2)-bridging water mol-ecule, forming one-dimensional chains propagating along [100]. The naphthalene-2,6-dicarboxylate ligands further inter-connect these chains into a three-dimensional framework, which has zigzag channels housing the water mol-ecules. Two naphthalene-2,6-dicarboxylate bridging ligands have their centroids located on crystallographic centres of inversion. One water O atom has a fixed site occupancy factor of 0.75.