Multifunctional Magnetic Materials Obtained by Insertion of a Spin‐Crossover Fe^III Complex into Bimetallic Oxalate‐Based Ferromagnets

Abstract

The syntheses, structures and magnetic properties of the compounds of formula [Fe(III)(sal(2)-trien)][Mn(II)Cr(III)(ox)(3)].CH(2)Cl(2) (1; H(2)sal(2)-trien=N,N'-disalicylidenetriethylenetetramine, ox=oxalate), [Fe(III)(sal(2)-trien)][Mn(II)Cr(III)(ox)(3)].CH(3)OH (2), [In(III)(sal(2)-trien)][Mn(II)Cr(III)(ox)(3)].0.25H(2)O.0.25CH(3)OH.0.25CH(3)CN (3), and [In(III)(sal(2)-trien)][Mn(II)Cr(III)(ox)(3)].CH(3)NO(2).0.5H(2)O (4) are reported. The structure of 1 presents a 2D honeycomb anionic layer formed by Mn(II) and Cr(III) ions linked through oxalate ligands and a cationic layer of [Fe(sal(2)-trien)](+) complexes intercalated between the 2D oxalate network. The structures of 2, 3, and 4 present a 3D achiral anionic network formed by Mn(II) and Cr(III) ions linked through oxalate ligands with [Fe(sal(2)-trien)](+) or [In(sal(2)-trien)](+) complexes and solvent molecules intercalated within the 3D oxalate network. The magnetic properties and Mössbauer spectroscopy of 1 and 2 indicate that these compounds undergo a long-range ferromagnetic ordering at around 5 K and a spin crossover of the intercalated [Fe(sal(2)-trien)](+) complexes above 130 K, which is complete in the case of 1. The magnetic properties of the compounds 3 and 4 confirm the ferromagnetic ordering of the bimetallic oxalate network.

Recent Advances on Anilato-Based Molecular Materials with Magnetic and/or Conducting Properties

“…In the last 20 years many efforts have been addressed to add in these materials a further physical property by playing with the functionality of the A + cations located between the bimetallic layers. This strategy produced a large series of multifunctional molecular materials where the magnetic ordering of the bimetallic layers coexists or even interacts with other properties arising from the cationic layers, such as paramagnetism [2,[76][77][78][79][80], non-linear optical properties [2,81,82], metal-like conductivity [83,84], photochromism [2,81,85,86], photoisomerism [87], spin crossover [88][89][90][91][92][93], chirality [94][95][96][97], or proton conductivity [2,98,99]. Moreover, it is well-established that the ordering temperatures of these layered magnets are not sensitive to the separation determined by the cations incorporated between the layers, which slightly affects the magnetic properties of the resulting hybrid material, by emphasizing its 2D magnetic character [2,[75][76][77][78][79][80]95,100,101].…”

“…These molecular complexes, which represent one of the best examples of molecular bistability, change their spin state from low-spin (LS) to high-spin (HS) configurations and thus their molecular size, under an external stimulus such as temperature, light irradiation, or pressure [161,162]. Two-dimensional (2D) and three-dimensional (3D) bimetallic oxalate-based magnets with Fe(II) and Fe(III) spin-crossover cationic complexes have been obtained, where changes in size of the inserted cations influence the magnetic properties of the resulting materials [89,90,92,93]. By combining [Fe III (sal 2 -trien)] + (sal 2 -trien = N,N -disalicylidene triethylenetetramine) cations with the 2D Mn II Cr III oxalate-based network, a photoinduced spin-crossover transition of the inserted complex (LIESST effect), has been observed unexpectedely; this property infact is very unusual for Fe(III) complexes.…”

Electronic structures in the triplet states of polypyridine iridium(III) complexes

“…From the magnetic susceptibility measurement, adsorbed O 2 was found to have antiferromagnetic ground state. But the meta-magnetic like behavior observed in the high-field magnetization process could not be explained by Heisenberg antiferromagnetic dimer model [1].…”

“…From the magnetic susceptibility measurement, adsorbed O 2 was found to have antiferromagnetic ground state. But the meta-magnetic like behavior observed in the high-field magnetization process could not be explained by Heisenberg antiferromagnetic dimer model [1].In the case of CuCHD (Cu-trans-1,4-cyclohexanedicarboxylic acid) [2] that have comparable size of nanochannels with CPL-1, O 2 molecules were also adsorbed forming dimer as same as CPL-1. The adsorbed O 2 dimer has H-geometry corresponding to the ground state with S=0 at 20 K and the geometry changed to S-type with increasing temperature.…”

Spin-Singlet Transition in the Magnetic Hybrid Compound from a Spin-Crossover Fe(III) Cation and π-Radical Anion

“…Thus the utilization of electronic and structural transformation accompanying SCO can lead to potential applications of display, memory, sensing and electronic devices [3,4]. One of the emergent fields of SCO research in the last decade is the development of multifunctional compounds between SCO and other solid-state electronic properties such as conductivity [5][6][7][8][9][10][11][12], magnetism [13][14][15][16][17][18][19][20][21][22][23], and optical properties [24,25]. The goal of this research is that one can design and synthesize a molecular solid whose electronic property can be controlled by external stimuli.…”