The second biggest family of TBC [8]-supported clusters belongs to homo-and heterometallic complexes of Co II . The first, and only homometallic cluster in the family is the aesthetically pleasing [HNEt3]2[Co II 2(H5TBC [8])2] (14) dimer made in 2007 (Fig. ). Ln = Gd (15b), Dy (15c), m = 10, n = 4). The complexes were synthesised from the solvothermal reaction of Ln(OAc)3•6H2O, Co(OAc)2•4H2O and H8TBC [8] in a basic dmf/MeOH solution (dmf = N,N-dimethylformamide). The CO3 2-originates form the fixation of atmospheric CO2 and the formate from the oxidation of MeOH. The structure of 15 (Fig. ) is rather unusual. Each half of the molecule consists of a central [Co2Ln2(µ4-O)] square. On one side of this square lies a [CoLn2(µ3-OH)] triangle which shares a vertex at the Ln site. On the other side of the square lies a [Co2Ln(µ3-OH)] triangle which shares the Co-Ln edge of the square. Both triangles are positioned approximately perpendicular to the square. The two remaining Ln ions link the two halves of the molecule together. Each half of the molecule contains one fully deprotonated TBC [8] ligand in the doublecone conformation, with each O(Ph) atom µ-bridging between neighbouring metal ions. Six of these link Co-Ln ions within each half of the cluster, while two bridge the two Ln ions in the central square to the two Ln ions that join the halves together. The Co II ions are of three types, two are six-coordinate and in distorted octahedral {CoO6} geometries, four are five-coordinate and in distorted trigonal bipyramidal {CoO5} geometries, and two are four coordinate and in distorted tetrahedral {CoO4} geometries. The Ln III ions are in two geometries, four being eight coordinate and in square antiprismatic {LnO8} geometries, and two being seven coordinate and in capped trigonal prismatic {LnO7} geometries. Magnetic studies of all three complexes showed the presence of competing (weak) ferro-and antiferromagnetic exchange interactions. The isostructural complexes [Ln III 4Co II 4(TBC [8])2O2(def)x(H2O)y] (Ln = Dy (16a, x=8, y=4); Er (16b), x=8, y=4; Y (16c), x=6, y=6; Fig. ) were published in 2017. They were synthesised from the solvothermal reaction of H8TBC [8], Co(OAc)2•4H2O and Ln(OAc)3•6H2O in a basic MeOH/def solution (def = N,N-diethylformamide) at T = 130 °C for 3 days. The metallic skeleton of 16 describes a {Ln III 4Co II 4} square antiprism, with the top and bottom faces being {Ln III 2Co II 2} squares with the 3d and 4f metal ions alternating around the square. These are connected by a central, planar µ4-O 2-ion. The upper and lower square faces are connected to each other through the presence of four µ3-H2O molecules. The inorganic core is sandwiched between two tail-to-tail, fully deprotonated TBC [8] ligands which adopt the double-cone conformation. In each case four of the O(Ph) atoms are µ-bridging between Co-Ln ions while the remaining four are monodentate, neighbouring pairs chelating to a single Ln ion. The coordination sphere of each metal ion is completed by a solvent molecule. The Ln III ions have two different geometries, two being eight-coordinate and square antiprismatic {LnO8}, and two being seven-coordinate with capped octahedral {LnO7} geometry. Likewise, the Co II ions possess two different geometries, five coordinate distorted trigonal bipyramidal (CoO5}, and six coordinate distorted octahedral {CoO6}. Magnetic studies reveal that the Dy analogue (16a) is a Single-Molecule Magnet (SMM), possessing frequency and temperature dependent out-of-phase (χ") signals in ac susceptibility studies. The ac susceptibility data were fitted to a model assuming a Raman/Orbach relaxation mechanism of the form ln τ = -ln [CT n + τ0 -1 exp(-Ueff/kBT)] to afford Ueff/kB = 10.38 K, τ0 = 9.8 × 10 -6 s, C = 1500 s -1 K -0.4 , n = 0.4. At the centre of the cluster lies a μ6-CO3 2-anion, generated in-situ from the fixation of atmospheric CO2, which templates the formation of a {Co6} wheel. The outer rim of this wheel is bridged alternately by three µ-OH -ions and three µ3-OH -ions, the latter also bridging to a Ln ion in the (Ln2TBC [8]} fragments. These are all positioned 'above' the {Co6} plane forming a bowl-shaped cage. The three, fully deprotonated, TBC [8] ligands adopt the double-cone conformation, each encapsulating a {Ln2} dimer and using two of their O(Ph) arms to bridge between the two metals, {Ln2(OR)3}. The third bridging O atom in the dimer is provided by either an acetate or methanol. Two of the O(Ph) arms are used to connect the {Ln2} dimer to the {Co6} wheel across the same edge as the µ3-OH -ions. The remaining three O(Ph) atoms are monodentate, with one per ligand protonated. The coordination spheres of all the Ln III ions are completed by a molecule of dmf, and result in either seven coordinate {LnO7} capped octahedra, seven coordinate capped {LnO7} trigonal or eight coordinate {LnO8} biaugmented trigonal prisms. Each Co II ion is five coordinate and in a distorted trigonal bipyramidal {CoO5} coordination geometry. Magnetic studies suggest that the Eu analogue exhibits spin glass behaviour, while the Dy version is an SMM. 17 (18) describes two [CoTh3O(OH)] tetrahedra, sharing a {Th2} edge (Fig. ). The µ4-O 2-ions sit in the centre of each tetrahedra, with the µ-OH -ions capping one {Th2} edge each. The hepta-deprotonated H1TBC [8] ligands adopt the double-cone conformation, with four O(Ph) atoms µ-bridging between neighbouring Co-Th (x3), Th-Th (x1) metal ions across edges of the {CoTh3} tetrahedra. The remaining four O(Ph) atoms are all terminally bonded to Th ions. The latter are eight coordinate and in distorted square antiprismatic {ThO8} geometries, while the two Co ions are both 5-coordinate {CoO5} and trigonal bipyramidal. The six dmf molecules sit in the hydrophobic calix [8]arene cavities, one terminally bonded to each of the Co and Th ions.