Self-assembly of a trigonal bipyramidal architecture with stabilisation of iron in three spin states.

Abstract

Self-assembly and characterisation of a supramolecular trigonal bipyramidal iron cage containing an [Fe (μ -F) (Fe ) ] star motif at its core is reported. The complex can be formed in a one step reaction using an heterotopic ligand that supports site-specific incorporation of iron in three distinct electronic configurations: low-spin Fe , high-spin Fe and high-spin Fe , with iron(II) tetrafluoroborate as the source of the bridging fluorides. Formation of a μ -F bridged mixed-valence Fe -Fe star is unprecedented. The peripheral high-spin Fe centres of the mixed-valence tetranuclear star incorporated in the iron cage are highly anisotropic and engage in F-mediated antiferromagnetic exchange with the central Fe ion.