There are also only three Mn-based clusters in the CSD, all published between 2011-2013. The first of these was the complex [Mn iii 2Na4(H5TBC [8])2(CO3)2(dmf)6] (25; Fig. ) which was made from the reaction of MnCl2•4H2O, H8TBC [8] and NaO2CCMe3 in a basic MeOH/dmf solution. The pivalate anion is not incorporated into the structure but its presence appears vital for cluster formation. We note with interest that the well-known complex [Mn6O2(O2CR)10(solvent)4] (R = CMe3, Ph) is often a major/minor product in Mn-H8TBC [8] reactions with certain carboxylates. The metallic skeleton of 25 contains a central {Na4} square, flanked on both sides by a Mn III ion. The metals are linked together by two µ5-CO3 2-ions, formed from the fixation of atmospheric CO2, which each bridge to all four Na ions and one Mn III ion on the same face of the square. The remaining bridging in the {Mn2Na4} moiety comes from two µ3-bridging and two µ-bridging dmf molecules. The former sit above/below the {MnNa2} triangles in the two halves of the molecule. The latter bridge between two Na ions across an edge of the {Na4} square. The presence of multiple bridging dmf molecules, and in two different coordination modes, is rather unusual. The calix [8]arene ligands adopt the pleated-loop conformation, sandwiching the inorganic core. They are triply deprotonated with six of the eight O(Ph) atoms being monodentate and each neighbouring pair chelating to a metal centre in the {MnNa2} triangle. The remaining two (neighbouring) HO(Ph) arms are uncoordinated. The six coordinate Mn III ions have their coordination spheres completed with two (trans) dmf ligands and are in Jahn-Teller (JT) distorted octahedral {MnO6} geometries, the JT axis being defined by the O(dmf)-Mn-O(dmf) vector. Examination of the extended structure of 25 reveals the formation of large and aesthetically pleasing infinite stacked tubular assemblies, and that packing of neighbouring tubules results in the formation of solvent-filled channels within the structure. The structure of 25 has some striking similarities to 24 (Fig. ) despite the different d-and s-block metals employed and the entirely different synthetic methodologies, highlighting perhaps the dominant structure directing role of calix [8]arene ligands. The presence of the bridging dmf molecules is similar to that seen in the vanadium chemistry described above.