Molecular magnetism and solid-phase transformations of Dy, Er, and Yb tropolonate complexes

Abstract

New complexes containing Dy, Er and Yb, namely, [LnT₃(H₂O)₂]·0.5H₂O (1Ln), [LnT₃HT]₂ (2Ln) and 2Dy_n, where HT = 2-hydroxycyclohepta-2,4,6-trien-1-one, were synthesized and structurally characterized. The coordination number of Ln in isolated compounds is 8, and the coordination site is LnO₈. The thermolysis of 1Ln and 2Ln results in the removal of coordinated and solvating water molecules and the formation of Ln₂OT₄. All synthesized compounds exhibit slow relaxation of magnetization under an external dc-field, and complex 1Dy exhibits slow relaxation even under zero dc-field. The diamagnetic dilution of 1Dy with an isomorphic yttrium complex resulted in the formation of 1DyY and allowed us to mitigate a considerable involvement of the quantum tunneling of magnetization (QTM) in the magnetization reversal in zero dc-field. The relaxation paths for 1Er and 2Er involve the Orbach mechanism, with the corresponding energy barriers determined to be 39 K and 33 K, respectively.