title: Stimuli responsive hybrid magnets: tuning the photoinduced spin-crossover in Fe(III) complexes inserted into layered magnets.
abstract: The insertion of a [Fe(sal2-trien)](+) complex cation into a 2D oxalate network in the presence of different solvents results in a family of hybrid magnets with coexistence of magnetic ordering and photoinduced spin-crossover (LIESST effect) in compounds [Fe(III)(sal2-trien)][Mn(II)Cr(III)(ox)3]·CHCl3 (1·CHCl3), [Fe(III)(sal2-trien)][Mn(II)Cr(III)(ox)3]·CHBr3 (1·CHBr3), and [Fe(III)(sal2-trien)][Mn(II)Cr(III)(ox)3]·CH2Br2 (1·CH2Br2). The three compounds crystallize in a 2D honeycomb anionic layer formed by Mn(II) and Cr(III) ions linked through oxalate ligands and a layer of [Fe(sal2-trien)](+) complexes and solvent molecules (CHCl3, CHBr3, or CH2Br2) intercalated between the 2D oxalate network. The magnetic properties and Mössbauer spectroscopy indicate that they undergo long-range ferromagnetic ordering at 5.6 K and a spin crossover of the intercalated [Fe(sal2-trien)](+) complexes at different temperatures T1/2. The three compounds present a LIESST effect with a relaxation temperature TLIESST inversely proportional to T1/2. The isostructural paramagnetic compound, [Fe(III)(sal2-trien)][Zn(II)Cr(III)(ox)3]·CH2Cl2 (2·CH2Cl2) was also prepared. This compound presents a partial spin crossover of the inserted Fe(III) complex as well as a LIESST effect. Finally, spectroscopic characterization of the Fe(III) doped compound [Ga0.99Fe0.01(sal2trien)][Mn(II)Cr(III)(ox)3]·CH2Cl2 (3·CH2Cl2) shows a gradual and complete thermal spin crossover and a LIESST effect on the isolated Fe(III) complexes. This result confirms that cooperativity is not a necessary condition to observe the LIESST effect in an Fe(III) compound.
authors.affiliation: Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, Catedrático José Beltrán 2, 46980 Paterna, Spain. miguel.clemente@uv.es
authors.forename: Miguel
authors.initials: M
authors.lastname: Clemente-León
authors.forename: Eugenio
authors.initials: E
authors.lastname: Coronado
authors.forename: Maurici
authors.initials: M
authors.lastname: López-Jordà
authors.forename: João C
authors.initials: JC
authors.lastname: Waerenborgh
authors.forename: Cédric
authors.initials: C
authors.lastname: Desplanches
authors.forename: Hongfeng
authors.initials: H
authors.lastname: Wang
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Létard
authors.forename: Andreas
authors.initials: A
authors.lastname: Hauser
authors.forename: Antoine
authors.initials: A
authors.lastname: Tissot
mesh_terms: D060526:Magnetic Fields; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D055668:Photochemical Processes
chemical_list: D009942:Organometallic Compounds