Inorganic Approach to Stabilizing Nanoscale Toroidicity in a Tetraicosanuclear Fe_(18)Dy_6 Single Molecule Magnet

摘要

Cyclic coordination clusters (CCCs) are proving to provide an extra dimension in terms of exotic magnetic behavior as a result of their finite but cyclized chain structures. The Fe_(18)Dy_6 CCC is a Single Molecule Magnet with the highest nuclearity among Ln containing clusters. The three isostructural compounds [Fe_(18)Ln_6(μOH)_6(ampd)_(12)(Hampd)_(12)(PhCO_2)_24](NO_3)_6-38MeCN for Ln = Dy~(III) (1), Lu~(III) (2), or Y~(III) (3), where H_2ampd = 2-amino-2-methyl-l,3-propanediol, are reported. These can be described in terms of the cyclization of six {Fe_3Ln(μOH)(ampd)_2(Hampd)_2(PhCO_2)_4}+ units with six nitrate counterions to give the neutral cluster. The overall structure consists of two giant Dy_3 triangles sandwiching a strongly antiferromagnetically coupled Fe_(18) ring, leading to a toroidal arrangement of the anisotropy axis of the Dy ions, making this the biggest toroidal arrangement on a molecular level known so far.