Spins on a curved surface: an Fe(III)14 ferracalixarene.

ABSTRACT

The synthesis of the high-nuclearity Fe(III)14 coordination cluster [Fe14(µ3-O)6(µ3-OH)4(µ-OH)3Cl11(dea)4(Hdea)3]Cl·H2O·27MeCN (1) is reported (in which deaH2 = diethanolamine). X-ray crystallographic analysis revealed that compound 1 crystallises in the cubic space group Im3 with Z = 24 and 8 independent Fe centres. Unusually for an Fe(III) coordination cluster, the Fe(III) centres in 1 adopt a range of 4, 5 and 6 coordinate geometries. Complex 1 presents a ferracalixarene topology which can be described in terms of a "half tennis ball" structure and binds a chloride anion guest via multiple hydrogen bonds. The curvature in the structure induced by this topology affects the overall spin structure. A ground spin state of S = 7 is proposed using a combination of magnetic susceptibility data and density functional theory (DFT) calculations.