title: Slow magnetic relaxation in a mononuclear eight-coordinate cobalt(II) complex.
abstract: The quest for the single-molecular magnets (SMMs) based on mononuclear transition-metal complexes is focused on the low-coordinate species. No transition-metal complex with a coordination number of eight has been shown to exhibit SMM properties. Here the magnetic studies have been carried out for a mononuclear, eight-coordinate cobalt(II)-12-crown-4 (12C4) complex [Co(II)(12C4)2](I3)2(12C4) (1) with a large axial zero-field splitting. Magnetic measurements show field-induced, slow magnetic relaxation under an applied field of 500 Oe at low temperature. The magnetic relaxation time τ was fitted by the Arrhenius model to afford an energy barrier of Ueff = 17.0 cm(-1) and a preexponential factor of τ0 = 1.5 × 10(-6) s. The work here presents the first example of the eight-coordinate, mononuclear, 3d metal complex exhibiting the slow magnetic relaxation.
authors.affiliation: State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Jin-Mei
authors.initials: JM
authors.lastname: Wei
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wernsdorfer
authors.forename: Xue-Tai
authors.initials: XT
authors.lastname: Chen
authors.forename: Yi-Quan
authors.initials: YQ
authors.lastname: Zhang
authors.forename: You
authors.initials: Y
authors.lastname: Song
authors.forename: Zi-Ling
authors.initials: ZL
authors.lastname: Xue