Single-Molecule Magnetism in a Pentacoordinate Cobalt(II) Complex Supported by an Antenna Ligand

Abstract

Pentacoordinate complex [CoL(3)Cl2] with a tridentate antenna-like ligand L(3) forms a dimer held by short π-π stacking with head-to-head contacts at 3.4 Å. The direct-current (dc) magnetic susceptibility and magnetization data confirm weak ferromagnetic interaction and a large-magnetic anisotropy, D/hc = 150 cm(-1) and E/hc = 11.6 cm(-1). The system shows superparamagnetic behavior at low temperature that depends upon the applied magnetic field. At Bdc = 0.2 T, a low-frequency peak at the out-of-phase susceptibility is seen (ν ∼ 0.3 Hz), whereas the onset of the second peak appears at ν > 1500 Hz, indicating the existence of two slow relaxation processes.

The rise of 3-d single-ion magnets in molecular magnetism: towards materials from molecules?

“…A penta-coordinate Co( ii ) SIM, [CoL 3 Cl 2 ] ( 59 ) (L 3 = 4-hept-1-ynyl-2,6-dipyrazol-l-ylpyridine),66 has also been reported by Boča. The aromatic tridentate ligand facilitates π–π stacking of the discrete molecules, thus forming dimers and leading to intermolecular ferromagnetic interactions between metal centres.…”

Magnetic anisotropy in two- to eight-coordinated transition–metal complexes: Recent developments in molecular magnetism

“…For 75 with distorted squarebased TP geometry (Fig. 26), much higher magnetic anisotropy was found with D = 151 cm -1 [107]. However, this compound exhibits slow magnetic relaxation with a rather modest effective energy barrier for magnetization reversal of U eff = 9.4 cm -1 under an applied dc field of 2000 Oe.…”

Solvent‐Controlled Phase Transition of a CoII‐Organic Framework: From Achiral to Chiral and Two to Three Dimensions

“…These values span rangest ypicalf or hexacoordinate Co II complexes. [13] The magnetic data for 1·CH 3 OH and 1·CH 3 CH 2 OH exhibit as imilarb ehavior to 1.T hus the incorporation of the solvent molecules into the crystal lattice does not alter the overall magnetic behavior,a lthough the solvents are involved in the phase transition. There is no noticeable change in the magnetization at the structural transition.…”