Two hexanuclear [Co2III-Ln4III] clusters including a [Co2III-Dy4III] single molecule magnet

Abstract

Structural determination and magnetic studies of two 3d-4f hexanuclear [CoIII2LnIII4(μ3-OH)2(NO3)4(OAc)4L4(DMF)2]·2C2H5OH [Ln = Dy(1), Gd(2); H2L = (E)-4-chloro-2-(((2-(hydroxymethyl)phenyl)imino)methyl)phenol] clusters are reported. Single-crystal X-ray diffraction studies reveal that the centrosymmetric hexanuclear metallic core is composed of a defect-dicubane Ln4 moiety and two CoIII ions. The Ln4 defect-dicubane central core is composed of four LnIIIions, which are supported by two oxygen atoms from the acetate groups, two alkoxo groups and two μ3-OH groups, which are displaced above and below the Ln4plane. And two CoIII ions (one positioned above and one below the Ln4 plane) are linked to the defect-dicubane unit through two alkoxo groups and two phenoxido groups. This structure gives a CIS chair-like topology. Variable temperature direct current (dc) magnetic susceptibility measurements reveal the LnIII ions in complex 1 are ferromagnetic coupling, while antiferromagnetic coupling in 2. Complex 1 also displays an out-of-phase signal in the alternating current susceptibility indicating slow relaxation of the magnetization with Ueff = 31.6 K and τ0 = 5.66 × 10−6 s.