The synthetic versatility and accessibility of p-tert-butylcalix [n]arenes have seen them employed in an incredibly diverse range of chemistry. In coordination chemistry, the tetraphenolic pocket of p-tertbutylcalix [4]arene (H4[TBC [4], Fig. ) presents an attractive ligand motif for the construction of transition metal (TM) and lanthanide metal (LnM III ) metalloligands that can self-assemble into larger, polymetallic cages. Structurally, this means the (TM-TBC [4])/(LnM-TBC [4]) moiety acts as a capping fragment in the resulting metallic skeleton, with some or all of the phenolato O-atoms further bridging to other metal ions. When these metal ions are paramagnetic, the clusters can display fascinating magnetic behaviour including, for example, single-molecule magnetism, spin frustration or an enhanced magnetocaloric effect. The dominant structure-directing role of the calix [4]arene also means that, in some cases, analogous structural topologies can be made with different metals and with metals in a variety of oxidation states, allowing detailed magneto-structural studies. The tetraphenolato pocket of TBC [4] 4-is particularly well suited to bonding Jahn-Teller (JT) distorted ions such as octahedral Mn III because it will preferentially coordinate metals possessing four short equatorial bonds. Indeed, this ability has been exploited to isolate a number of polymetallic Mn clusters, including [Mn III Mn II ], [Mn III Mn II ]2, [Mn III 2Mn , [Mn III 3Mn , [Mn III 7Mn II ], and [Mn III 8Mn . In each case the Mn III ions sits in the TBC [4] pocket, and the (Mn III -TBC [4]) metalloligand further bridges to additional metal ions, often encapsulating a polymetallic metal-oxo/hydroxo cluster. Extension of the chemistry to the related to 2,2'-bis-p-t Bu-calix [4]arene (H8-bisTBC [4], Fig. ) in which two H4TBC [4]s are linked via a methylene bridge allows expansion from a single organic scaffold possessing one to two Mn III -TBC [4] metalloligands. Indeed, the conformational flexibility (ring inversion) of H8-bisTBC [4], provides an organic skeleton with eight proximal phenolic O-atoms, and this potentially offers a route to larger polymetallic cages. Indeed, in Mn chemistry this has led to the isolation of [Mn III 4Mn , [Mn III 6Mn , [Mn III 4Mn , [Mn IV 2Mn III 10Mn , and [Mn III 10Mn . Here we extend this family of compounds to include heterometallic species by reporting the synthesis, structure and magnetic properties of [Mn III 3Na6(TBC [4]