The second Mn-based cluster published employed a heteroleptic ligand strategy which exploited the complementary ligand bridging modes of H8TBC [8] and phenyl salicylaldoxime (Ph-saoH2) to drive the formation of a heterovalent {Mn III Mn IV } dimer. Thus, the reaction of Mn(NO3)2•4H2O, H8TBC [8] and Ph-saoH2 in a basic dmf/MeOH solution afforded [Mn III Mn IV (H4TBC [8])(Ph-sao)(μ-OMe)(dmf)2] (26; Fig. ). The magnetic core of 26 is a [Mn III O(Me)O(Ph)(NO)Mn IV ] moiety in which the two Mn ions are triply bridged by a single µ-OMe ion, a single µ-O(Ph) atom from the calix [8]arene, and the -N-O-oxime unit of Ph-sao 2-. The Mn III ion has its coordination sphere completed by the terminally bonded alkoxide O-atom of Ph-sao 2-and a molecule of dmf, with the O(dmf)-Mn-O(Ph) vector defining the JT axis. There is also a single dmf coordinated to the Mn IV ion. Both Mn ions are six coordinate and in distorted octahedral geometries. The quadruplydeprotonated H4TBC [8] ligand adopts a conformation that is best described as being somewhere between a double-cone and a pleated-loop, wherein three phenol moieties adopt a cone orientation and the other five resemble a regular pleated-loop. The four deprotonated O(Ph) atoms adopt different coordination modes, three being monodentate and the fourth µ-bridging. The four protonated HO(Ph) arms are non-coordinated. It would appear therefore that the presence of the bulky phenolic oxime prevents full adoption of either of the more common calix [8]arene conformations, and restricts the nuclearity of the complex formed. The complex [Mn II 5(H4TBC [8])(OH)2(OMe)1.5(HCOO)(OAc)0.5 (O2CNMe2)(dmf)5] (27; Fig. ) was synthesised via the solvothermal (T = 130 °C, 3 days) reaction of Mn(OAc)2•4H2O, H8TBC [8] and KCl in a basic MeOH/dmf solution. Neither K + or Cl -are incorporated into the structure of the product, but it would appear that addition of the salt is required for 27 to form. The dimethylcarbamate and formate anions are generated insitu from the decomposition of dmf/oxidation of MeOH, respectively. The metallic skeleton of 27 describes a {Mn5} square based prism, with the apex connected to the square base via a combination of µ3-OMe and µ3-OH ions. The four Mn ions in the base are further connected by the µ3-O2CNMe2 ligand that sits below the square. All five Mn II ions are six coordinate and in distorted octahedral {MnO6} geometries. Each has a single terminally coordinated dmf molecule directed above the square, with the apical Mn ion bonded to an additional carboxylate (OAc/O2CH) ligand. The calix [8]arene is tetra-deprotonated, H4TBC [8] and sits below the {Mn4} square in the pleated-loop conformation, each neighbouring pair of O(Ph) atoms chelating to a single Mn II ion. Magnetic susceptibility studies revealed the presence of weak antiferromagnetic exchange (J = -2-3 cm -1 ) between neighbouring Mn II ions. 25