Half-integer spin heptanuclear single-molecule magnet with an unusual Mn(III)6Mn(II) exchange-coupled core

Inorg Chem. 2012 Apr 16;51(8):4448-57. doi: 10.1021/ic2019154. Epub 2012 Apr 3.

Abstract

The synthesis, X-ray crystallography, magnetic properties, and high-field electron paramagnetic resonance (HFEPR) of a new heptanuclear manganese complex [Mn(7)(heamp)(6)](ClO(4))(2)·4CH(2)Cl(2)·H(2)O (complex 2), in which heampH(3) is 2-[N,N-di(2-hydroxyethyl)aminomethyl]phenol (compound 1), is reported. Complex 2 has a hexagonal, disk-shaped topology and contains six Mn(III) ions and a central Mn(II) ion. It crystallizes in the monoclinic space group P2(1)/c with two molecular orientations. Consideration of the cluster topology, together with variable-temperature and variable-field DC magnetic susceptibility data, suggest that complex 2 exists in a half-integer, S = (19)/(2) ± 1 spin ground state, with appreciable uniaxial zero-field splitting (D = -0.16 cm(-1)). AC magnetic susceptibility measurements clearly show out-of-phase signals, which are frequency- and temperature-dependent, indicating slow magnetization relaxation behavior. An analysis of the relaxation data employing the Arrhenius formula yielded an effective relaxation barrier of 12.9 cm(-1). Simulations of HFEPR studies agree with the assignment of an S ≈ (19)/(2) spin ground state, with g = 1.96, D = -4.71 GHz (-0.16 cm(-1)), and a longitudinal fourth-order zero-field splitting parameter B(4)(0) = -2.7 × 10(-4) GHz (-9.0 × 10(-6) cm(-1)).

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Ethanolamines / chemistry
  • Ligands
  • Magnets / chemistry*
  • Manganese / chemistry*
  • Models, Molecular
  • Molecular Conformation
  • Organometallic Compounds / chemistry*
  • Phenol / chemistry

Substances

  • Ethanolamines
  • Ligands
  • Organometallic Compounds
  • Phenol
  • Manganese
  • diethanolamine