LAUSR

The reaction between MnCl2·4H2O, 2,2'-bis-p-tBu-calix[4]arene (H8L1) and 2-(hydroxymethyl)pyridine (hmpH) in a basic dmf/MeOH solution results in the formation of the complex [MnIII10MnII4(L1)3(hmp)4(μ3-O)4(μ3-OH)2(MeOH)4(dmf)6](dmf)4 (6) upon vapour diffusion of petroleum ether into the mother liquor. The crystals are in the monoclinic space group C2/c, with the asymmetric unit (ASU) comprising one half of the molecule. The structure describes a large S-shaped cluster (∼40 Å top to tail) where the unusual syn and anti conformations of the calixarene ligands results in two binding pockets each containing a [MnIII5MnII2] moiety comprised of two perpendicular, vertex-sharing [Mn4] butterflies. One butterfly possesses a [MnIII4O4] core and the second a [MnIII2MnII2O3] unit with the MnII ions in the central body positions. Magnetic susceptibility and magnetisation measurements reveal weak exchange interactions between the metal centres.