Inorganic Approach to Stabilizing Nanoscale Toroidicity in a Tetraicosanuclear Fe18Dy6 Single Molecule Magnet

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 Fe18Dy6 CCC is a Single Molecule Magnet with the highest nuclearity among Ln containing clusters. The three isostructural compounds [Fe(18)Ln(6)(mu-OH)(6)(ampd)(12)(Hampd)(12)(PhCO2)(24)](NO3)(6)center dot 38MeCN for Ln = Dy-III (1), Lu-III (2), or Y-III (3), where H(2a)mpd = 2-amino-2-methyl-1,3-propanediol, are reported. These can be described in terms of the cyclization of six {Fe(3)Ln(mu OH)(ampd)(2)(Hampd)2(PhCO2)(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.