Hexanuclear Co₄Dy₂, Zn₄Dy₂, and Co₄Y₂ Complexes with Defect Tetracubane Cores: Syntheses, Structures, and Magnetic Properties

Abstract

A hexanuclear heterometallic cluster of composition [Dy2Co4(L)4(NO3)2(OH)4(C2H5OH)2] ⋅ 2 C2H5OH (1) was synthesized by employing a Schiff base 2‐(((2‐hydroxy‐3‐methoxybenzyl) imino)methyl)‐4‐methoxyphenol (H2L) as ligand and utilizing Dy(NO3)3 ⋅ 6H2O and Co(NO3)2 ⋅ 6H2O as metal ion sources. X‐ray single‐crystal diffraction analysis indicated that complex 1 contains a defect tetracubane core and possesses central symmetric structure, with two DyIII ions being in the central body position of the molecule and four CoII ions being arranged at the outer sites. Magnetic studies reveal that complex 1 behaves as single‐molecule magnet (SMM) with energy barrier of 27.50 K. To investigate the individual contribution of DyIII and CoII ions to the SMM behavior, another two complexes of formulae [Dy2Zn4(L)4(NO3)2(OH)4] ⋅ 4CH3OH (2) and [Y2Co4(L)4(NO3)2(OH)4(C2H5OH)2] ⋅ 2 C2H5OH (3) were prepared. Complexes 1 and 3 are isomorphous. The coordination geometries of DyIII ions in 1 and 2 are different. The DyIII ions are eight‐coordinated in 2 and nine‐coordinated in 1. Complex 2 exhibits SMM behavior with energy barrier of 69.67 K, but complex 3 does not display SMM property. These results reveal that the SMM behaviors of 1 and 2 are mainly originated from DyIII ions. It might be the higher symmetry of DyIII ions in 2 that results in the higher energy barrier.