Intracluster interactions in “butterfly” {Fe3LnO2} molecules

Abstract The magnetization contributions of the Fe 3 and Ln subcluster in the “butterfly” molecule [Fe 3 Ln(μ 3 -O) 2 (CCl 3 COO) 8 (H 2 O)(THF) 3 ], in brief {Fe 3 LnO 2 }, with Ln=Lu, Gd, Tb, Dy and Ho, have been determined by a combination of vibrating sample magnetometry and x-ray circular magnetic dichroism at low temperature and magnetic field up to 14 T. These contributions have been explained in terms of an effective spin model where the Fe 3 is described by a S Fe 3 = 5 / 2 spin, Gd by an isotropic J =7/2, Dy by a Kramers doublet, and non-Kramers ions Tb and Ho by a ligand field split doublet. The intracluster interactions J FeLn have been found to amount to a few K.