title: Importance of out-of-state spin-orbit coupling for slow magnetic relaxation in mononuclear Fe(II) complexes.
abstract: Two mononuclear high-spin Fe(II) complexes with trigonal planar ([Fe(II)(N(TMS)(2))(2)(PCy(3))] (1) and distorted tetrahedral ([Fe(II)(N(TMS)(2))(2)(depe)] (2) geometries are reported (TMS = SiMe(3), Cy = cyclohexyl, depe = 1,2-bis(diethylphosphino)ethane). The magnetic properties of 1 and 2 reveal the profound effect of out-of-state spin-orbit coupling (SOC) on slow magnetic relaxation. Complex 1 exhibits slow relaxation of the magnetization under an applied optimal dc field of 600 Oe due to the presence of low-lying electronic excited states that mix with the ground electronic state. This mixing re-introduces orbital angular momentum into the electronic ground state via SOC, and 1 thus behaves as a field-induced single-molecule magnet. In complex 2, the lowest-energy excited states have higher energy due to the ligand field of the distorted tetrahedral geometry. This higher energy gap minimizes out-of-state SOC mixing and zero-field splitting, thus precluding slow relaxation of the magnetization for 2.
authors: Department of Chemistry, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
authors: Po-Heng
authors: PH
authors: Lin
authors: Nathan C
authors: NC
authors: Smythe
authors: Serge I
authors: SI
authors: Gorelsky
authors: Steven
authors: S
authors: Maguire
authors: Neil J
authors: NJ
authors: Henson
authors: Ilia
authors: I
authors: Korobkov
authors: Brian L
authors: BL
authors: Scott
authors: John C
authors: JC
authors: Gordon
authors: R Tom
authors: RT
authors: Baker
authors: Muralee
authors: M
authors: Murugesu