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

Abstract

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)6L6]OH·1.5CH3CN (1) and [NaMn(III)6L6]OH·CH3OH·0.75H2O (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 [Fe6(OCH2)12] or [Mn6(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 ST = 0 or ST = 12 ground spin state, respectively. The magnetic behavior of the two clusters indicates antiferromagnetic coupling between the iron(III) centers in 1 and ferromagnetic coupling between the manganese(III) centers in 2.