The final Dy-based cluster reported is the complex [NaDy III (H6TBC [8])(OAc)2(dmf)3] (37; Fig. ), made from the reaction of Dy(OAc)3•6H2O, H8TBC [8], 1,1,1-tris(hydroxymethyl)ethane (thmeH3) and NEt3 in dmf/ethyl acetate (Fig. ). The doubly deprotonated H6TBC [8] ligand adopts the pleated-loop conformation, with the two neighbouring deprotonated O(Ph) atoms chelating the Dy ion. The two OAc -ligands also chelate to the Dy ion, using one O atom to µ-bridge to the Na ion. The coordination geometry of the Dy is completed with one molecule of dmf. The resulting {DyO8} environment is best described as distorted triangular dodecahedron. The Na ion is five-coordinate and has a distorted square pyramidal {NaO5} geometry, the remaining bonds comprising one molecule of dmf and two neighbouring, protonated O(Ph) atoms from the calix [8]arene. Interestingly, the {NaDy} lies outwith the H6TBC [8] plane, perhaps due to the bridging acetates being located on the same side of the {NaDy} dimer. The role of the thmeH3 ligand in the reaction is unclear, but its addition appears necessary for the isolation of the product. Complex 37 is a field induced SMM, albeit with a very small Ueff value. Replacing DyCl3•6H2O with GdCl3•6H2O in an otherwise identical reaction to that which produces 36 leads to the isolation of the complex [Gd )2(CO3)4(HCOO)2(dmf)8] (38; Fig. ). The metallic skeleton of 38 conforms to the 26 th Johnson solid (J26), the gyrobifastigium. This 8-vertex polyhedron is composed of four squares and four triangles constructed around a central square plane. It is perhaps best envisioned as two triangular prisms sharing a square face, with one prism given a quarter-turn. The metallic core is held together by a combination of two µ5-CO3 2-, three µ4-CO3 2-and two syn, syn, µ-HCOO - ligands. The CO3 2-and HCOO -ligands are derived from the fixation of atmospheric CO2 and the oxidation of MeOH, respectively. Both are commonly observed in Ln cluster chemistry, and especially so under solvothermal (high temperature, high pressure) reaction conditions. The two calix [8]arenes sandwich the inorganic core of the complex and are singly protonated, H1TBC [8], the proton being shared between O(Ph) neighbours which are all are terminally coordinated. Each ligand bonds to a total of five Gd centres, all being seven coordinate and in distorted pentagonal bipyramidal {GdO7} geometries. It is interesting to note that complex 38 contains no O 2-/OH -ions, in contrast to 33-36 despite the similarities in synthetic methodologies. It is also clear the that CO3 2-ions generated in-situ have acted as their "replacement". In turn, this suggests that deliberately incorporating carbonate ions into this chemistry (and other Ln chemistry) would be a fruitful source of new complexes. The magnetic properties of 38 were not reported.