Field-Induced Slow Magnetic Relaxation in Mononuclear Cobalt(II) Complexes Decorated by Macrocyclic Pentaaza Ligands

Abstract

Two cobalt(II) complexes [CoL1](OTf)2 (1, L1 = 6,6′′-di(anilino)-4′-phenyl-2,2′:6′,2′′-terpyridine) and [CoL2](OTf)2·MeOH (2, L2 = 6,6′′-di(N,N-dimethylamino)-4′-phenyl-2,2′:6′,2′′-terpyridine) were synthesized and characterized. Crystal structure analyses showed that the spin carries were coordinated by five N atoms from the neutral pentaaza ligands, forming distorted trigonal bipyramidal coordination environments. Ab initio calculations revealed large easy-axial anisotropy in complexes 1 and 2. Magnetic measurements suggest that complexes 1 and 2 are field-induced single-molecule magnets, whose relaxations are mainly predominated by Raman and direct processes.

Keywords

• single-ion magnet
• cobalt(II)
• trigonal bipyramidal
• macrocyclic pentaaza ligand