Cobalt(II) Citrate Cubane Single-Molecule Magnet

Abstract

An investigation of the magnetic properties of the cobalt(II) citrate cubane [C(NH 2) 3] 8{Co 4(cit) 4}.4H 2O reveals that the cluster is a new cobalt(II) single-molecule magnet, with an energy barrier to reorientation of the magnetization, Delta E/ k B = 21 K, and tau 0 = 8 x 10 (-7) s. The compound displays distinct, frequency-dependent peaks in the out-of-phase (chi'') component of the ac magnetic susceptibility and magnetization versus field hysteresis loops that are temperature and sweep rate dependent. The hysteresis loops collapse at zero field due to very fast quantum tunneling of the magnetization (QTM).

Complex magnetic orders in small cobalt–benzene molecules

“…[8][9][10] More recently, X-ray magnetic circular dichroism spectroscopy (XMCD) has been used to determine independently the orbital-and spin-magnetic moments measured on a trapped and cooled gas of metal cluster ions. [11][12][13] Contrary to the SMMs, where the transition metal centers are surrounded by organic compounds and thus, protecting their magnetic moment, [14][15][16] the transition metal atoms in such organometallic clusters are in close proximity, leading to strong exchange interactions. Although these organometallic clusters made up of transition metal clusters and benzene rings share same magnetic properties with SMMs, their magnetism is much less studied.…”

Synthesis, Characterization, Magnetic Properties, and Topological Aspects of Isoskeletal Heterometallic Hexanuclear CoII4LnIII2 Coordination Clusters Possessing 2,3,4M6–1 Topology

“…Variable‐temperature direct‐current (dc) magnetic susceptibility data were collected for compounds 1 – 4 over the temperature range 1.8–300 K in an applied field of 0.1 T. The data are shown as χ M T vs. T plots in Figure . The χ M T product of compound Co II 4 Y III 2 ( 1 ) has a room‐temperature value of 11.13 cm 3 mol –1 K, which is typical for four uncoupled Co II ions, but larger than that for four free S = 3/2 spins ( χT = 7.50 cm 3 K mol –1 and g = 2.0) as a result of the presence of a significant spin orbital contribution in the susceptibility of octahedral high‐spin Co II , , . By lowering the temperature the value of χ M T gradually decreases and reaches a value of 2.17 cm 3 K mol –1 at 1.8 K (Figure ).…”

A Tetragonal 2D Array of Single‐Molecule Magnets with Modulated Collective Behavior

“…[11] We have prepared 1D and 2D compounds based on [Co 8À cubanes; however, the complexity of the polymers and a unique reversible crosslinking reaction between them in the solid phase at room temperature [12] have obviated a study of their magnetism. A recent report by Murrie 8À -based polymer demonstrates, for the first time, that these systems are not limited to two dimensions.…”