Syntheses, Crystal Structures, and Magnetic Properties of Two Cyclic Clusters Comprising Six Iron(III)/Manganese(III) Ions and Entrapping Sodium Ions

The reaction of iron or manganese salt with sodium 2-{[bis(2-hydroxyethyl)amino]methyl}-4-methylphenate (NaH2L) in CH3OH/CH3CN solution represents a good synthetic route to the cation molecular wheels [NaFe-(III)(6)L-6]OH center dot 1.5CH(3)CN (1) and [NaMn(III)(6)L-6]OH center dot CH3OH center dot 0.75H(2)O (2), respectively. Single-crystal X-ray diffractions show that six octahedrally coordinated iron(III) ions in 1 and manganese(III) ions in 2 define a ring and are linked by 12 bridging oxygen atoms from alkoxo groups. The resulting [Fe-6(OCH2)(12)] or [Mn-6(OCH2)(12)] skeleton has the remarkable property of acting as a host for a octahedrally coordinated sodium ion in the center of the ring. DC magnetic susceptibility measurements on complexes 1 and 2 reveal the presence of exchange interactions resulting in a S-T = 0 or S-T = 12 ground spin state, respectively. The magnetic behavior of the two clusters indicates antiferromagnetic coupling between the iron(III) centers in I and ferromagnetic coupling between the manganese(III) centers in 2.