The coordination chemistry of cobalt is (thus far) dominated by the Co II ion, albeit with just one homometallic cluster, a dimer. All other reported compounds are heterometallic, being either Co-f block or Co-s block species. The prevalence of heterometallic over homometallic compounds is reflective of that seen for vanadium above, and remains a common theme in what follows below. The metallic skeletons of Co-based compounds are often based on dimers and tetramers. The latter can be squares, butterflies or tetrahedra, with larger species also being based on these units, e.g. square-based pyramids and square antiprisms. The calix [8]arene ligands in these clusters display a variety of conformations and protonation levels from the doubly deprotonated H6TBC [8] to the fully deprotonated TBC [8], with the O(Ph) atoms bonding in both terminal (with neighbouring atoms chelating the same metal centre) and µ-bridging modes.