title: Cyanide Single-Molecule Magnets Exhibiting Solvent Dependent Reversible "On" and "Off" Exchange Bias Behavior.
abstract: The syntheses, structures, and magnetic properties of four new complex salts, (PPN){[Mn(III)(salphen)(MeOH)]2[M(III)(CN)6]}·7MeOH (Mn2M·7MeOH) (M = Fe, Ru, Os and Co; PPN(+) = bis(triphenylphosphoranylidene)ammonium cation; H2salphen = N,N'-bis(salicylidene)-1,2-diaminobenzene), and a mixed metal Co/Os analogue (PPN){[Mn(III)(salphen)(MeOH)]2[Co(III)0.92Os(III)0.08(CN)6]}·7MeOH were undertaken. It was found that all compounds exhibit switchable single-molecule magnet (SMM) and exchange-bias behavior depending on the interstitial methanol content. The pristine (PPN){[Mn(salphen)(MeOH)]2[Os(CN)6]}·7MeOH (Mn2Os·7MeOH) behaves as an SMM with an effective barrier for the magnetization reversal, (Ueff/kB), of 17.1 K. Upon desolvation, Mn2Os exhibits an increase of Ueff/kB to 42.0 K and an opening of the hysteresis loop observable at 1.8 K. Mn2Os·7MeOH shows also exchange-bias behavior with magnetic hysteresis loops exhibiting a shift in the quantum tunneling to 0.25 T from zero-field. The Fe(III) and Ru(III) analogues were prepared as reference compounds for assessing the effect of the 5d versus 4d and 3d metal ions on the SMM properties. These compounds are also SMMs and exhibit similar effects but with lower energy barriers. These findings underscore the importance of introducing heavy transition elements into SMMs to improve their slow relaxation of the magnetization properties. The (PPN){[Mn(III)(salphen)(MeOH)]2[Co(III)(CN)6]}·7MeOH (Mn2Co·7MeOH) analogue with a diamagnetic Co(III) central atom and the mixed Co/Os (PPN){[Mn(III)(salphen)(MeOH)]2[Co(III)0.92Os(III)0.08(CN)6]}·7MeOH (Mn2Co/Os·7MeOH) "magnetically diluted" system with a 9:1 Co/Os metal ratio were prepared in order to further probe the nature of the energy barrier increase upon desolvation of Mn2Os. In addition, inelastic neutron scattering and frequency-domain Fourier-transform THz electron paramagnetic resonance spectra obtained on Mn2Os·7MeOH and Mn2Os in combination with the magnetic data revealed the presence of anisotropic exchange interactions between Mn(III) and Os(III) ions.
authors.affiliation: Faculty of Chemistry, Jagiellonian University , Ingardena 3, 30-060 Kraków, Poland.
authors.forename: Dawid
authors.initials: D
authors.lastname: Pinkowicz
authors.affiliation: Department of Chemistry, Texas A&M University , College Station, Texas 77842-3012, United States.
authors.forename: Heather I
authors.initials: HI
authors.lastname: Southerland
authors.affiliation: Department of Chemistry, Texas A&M University , College Station, Texas 77842-3012, United States.
authors.forename: Carolina
authors.initials: C
authors.lastname: Avendaño
authors.affiliation: Department of Chemistry, Texas A&M University , College Station, Texas 77842-3012, United States.
authors.forename: Andrey
authors.initials: A
authors.lastname: Prosvirin
authors.affiliation: Department of Chemistry, Texas A&M University , College Station, Texas 77842-3012, United States.
authors.forename: Codi
authors.initials: C
authors.lastname: Sanders
authors.affiliation: Institute Néel , CNRS, BP 166, 25 Avenue de Martyrs, Grenoble, 38042 Cedex 9, France.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wernsdorfer
authors.affiliation: Department of Chemistry, University of Copenhagen , Universitetsparken 5, DK-2100 Copenhagen, Denmark.|CNRS, CRPP, UPR 8641, F-33600 Pessac, France.|Univ. Bordeaux, CRPP, UPR 8641, F-33600 Pessac, France.
authors.forename: Kasper S
authors.initials: KS
authors.lastname: Pedersen
authors.affiliation: Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland and Swiss Light Source, Paul Scherrer Insitut , CH-5232 Villigen PSI, Switzerland.
authors.forename: Jan
authors.initials: J
authors.lastname: Dreiser
authors.affiliation: CNRS, CRPP, UPR 8641, F-33600 Pessac, France.|Univ. Bordeaux, CRPP, UPR 8641, F-33600 Pessac, France.
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Clérac
authors.affiliation: Institut Nanospektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Kekulestr. 5, D-12489 Berlin, Germany.|Berlin Joint EPR Laboratory, Helmholtz-Zentrum Berlin für Materialien und Energie, Kekulestr. 5, D-12489 Berlin, Germany.
authors.forename: Joscha
authors.initials: J
authors.lastname: Nehrkorn
authors.affiliation: Heinz Meier-Leibnitz Zentrum (MLZ) and Physics Department, Technical University of Munich , Lichtenbergstr. 1, 85748 Garching, Germany.
authors.forename: Giovanna G
authors.initials: GG
authors.lastname: Simeoni
authors.affiliation: Institut Nanospektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Kekulestr. 5, D-12489 Berlin, Germany.|Berlin Joint EPR Laboratory, Helmholtz-Zentrum Berlin für Materialien und Energie, Kekulestr. 5, D-12489 Berlin, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Schnegg
authors.affiliation: Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Albert-Einstein-Str. 15, D-12489 Berlin, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Holldack
authors.affiliation: Department of Chemistry, Texas A&M University , College Station, Texas 77842-3012, United States.
authors.forename: Kim R
authors.initials: KR
authors.lastname: Dunbar