As for 1, deliberate addition of carbonate in the form of Na2CO3 or NaHCO3 increases the yield of 2, in this case approximately four-fold (see experimental section for details). Also as for 1, inspection of related chemistry with Cu II shows a similar structural expansion relationship upon moving from H4TBC [4] ligands to H8-bisTBC [4]. The structure of 2 is reminiscent of the biscalix [4]arene-supported cluster [Cu )2(NO3)(μ-OH)8(dmf)7][OH], whose metallic skeleton also describes a (centred) tetra-capped square prism (Fig. ). Interestingly the latter contains an encapsulated and disordered Cu II ion at its centre. Like the [Cu9] cages, neighbouring vertices in the square prism in [Cu13] are linked to each other through µ-OH -bridges, making [Mn6Na6] (2) "taller and thinner" than the "shorter and wider" [Cu13]. Attempts to make the 'exact' [Mn /[Mn analogues of [Cu / [Cu in our laboratory have failed thus far, presumably (or at least in part) due to the very strong preference for the metal ion to be Mn III when housed in the TBC [4] (or C [4]) polyphenolic pocket. Indeed, there are no examples of Mn-based TBC [4] structures in the CCDC where Mn II ions are coordinated in the TBC [4] pocket, and all reactions between H4TBC [4] and Mn II salts in basic solutions under standard conditions reported thus far lead to the isolation of [Mn III 2Mn II 2(OH)2(TBC [4])2(solvent)6] or analogues thereof. The structure of the latter describes a [Mn III 2Mn butterfly (or near planar diamond) in which the two 'body' Mn II ions are encapsulated by two 'wing' Mn III -(TBC [4]) metalloligands. The addition of Group I metal ions to the reaction (here Na), and the insitu generation of carbonate, clearly alters the reaction pathway, leading to the isolation of [Mn3Na6] and [Mn6Na6] multiply capped trigonal and square prisms. The average metal oxidation state in 1 and 2 is 1.67 and 2.00, respectively, perhaps suggesting that these prisms are the preferred topology for TBC [4]-supported clusters of metal ions in lower oxidation states (≤2). Interestingly, there are zero TBC [4]-supported homometallic clusters of Fe II , Co II or Zn II reported in the literature, so it will be intriguing to discover the coordination chemistry of these metal ions. Likewise, it will be interesting to see if the incorporation of other Group I metal ions (Li, K, Cs) leads to the same structure types, and how this might change through the use of Group II metal ions (Mg-Ba). Similarly, the TBC [4]-based coordination chemistry of other combinations of M III -M I ions remains to be explored, as does the deliberate and systematic employment of the carbonate ion as a bridging ligand.