Repeating the reaction that produces 33 but using a different solvent combination (MeOH/dmf) and in the presence of NH4ClO4 results in the formation of [Ce IV 6O4(H2TBC [8])2(OMe)4(dmf)6] (35; Fig. ). The metallic skeleton of 35 is a slightly 'flattened' or 'squashed' [Ce6] octahedron. The two apical sites are connected to the four ions in the square plane (and to each other) via two µ4-O 2-ions, four µ-OMe -ions and four µ-O(Ph) atoms from the H2TBC [8] ligands. The remaining two, near linear, µ-O 2-ions each link neighbouring Ce IV ions across an edge of the square plane. Each H2TBC [8] exists as a hexa-anion -there is one intra-ligand H-bond between neighbouring O(Ph) atoms per molecule and one inter-ligand H bond -and bridges three Ce IV ions across one triangular face of the octahedron. The dmf molecules again occupy the calixarene cavities. All six Ce IV ions are eight coordinate and in square antiprismatic {CeO8} geometries. The addition of NH4ClO4 to the reaction seems critical to the formation of 35 even though neither cation or anion is incorporated into the cluster. Repeating the reaction that produced 34 but using DyCl3•6H2O in a basic dmf/MeOH solvent combination and under solvothermal conditions (T = 130°C, 24 hrs) results in the formation of [Dy III 7O2(OH)4(H1TBC [8])(H2TBC [8])(dmf)9] (36; Fig. ). The metallic skeleton of 36 describes a distorted, capped octahedron. The central cavity is again occupied by two µ4-O 2-ions, with the capping Dy III ion connected to the octahedron through a combination of two µ3-OH -ions and one µ-OH -ion. The remaining OH -ion µ-bridges between two Dy III ions in the square plane of the octahedron. The two calix [8]arene ligands are mono-and doubly deprotonated, respectively. In the former the single proton is shared between neighbouring O(Ph) atoms, both of which are terminally coordinated. This ligand bridges a total of six Dy III ions. For the latter, the two protonated arms are bonded terminally with very large Dy•••O distances. This ligand bridges a total of five Dy III ions. The Dy III ions are of two types: eight coordinate and in square antiprismatic {LnO8} geometries, or seven coordinate and in pentagonal bipyramidal {LnO7} geometries. The remaining metal coordination sites are filled with terminally bonded dmf molecules. The magnetic properties of 32, 34 and 36 were not reported. Fig. The structure of compound (35). Colour code: Ce = lime green, O = red, N = blue, C = grey. H atoms omitted for clarity.