Anisotropic magnetic properties and magnetic ordering in molecular decamethylferrocenium tetracyanoethanide

Calorimetric Investigation of Phase Transitions Occurring in Molecule-Based Magnets

“…Consequently, the magnitude of the interaction anisotropy is expected to be J ⊥ / J ∥ = 0.33. This value agrees well with J ⊥ / J ∥ = 0.30 derived from the magnetic susceptibility for single crystals . The calorimetric result suggesting a very strong Ising character of the magnetic interaction, J ⊥ / J ∥ < 0.5, supports the conclusion obtained from the single-crystal susceptibility.…”

“…This value agrees well with J ⊥ /J | ) 0.30 derived from the magnetic susceptibility for single crystals. 112 The calorimetric result suggesting a very strong Ising character of the magnetic interaction, J ⊥ /J | < 0.5, supports the conclusion obtained from the single-crystal susceptibility. Close examination of the magnetic elementary excitations in the ordered phase provides more evidence for the strong Ising character.…”

Pressure Induced Crossover between a Ferromagnetic and a Canted Antiferromagnetic State for [Bis(pentamethylcyclopentadienyl)-iron(III)][Tetracyanoethenide], [FeCp2*][TCNE]

“…Organic-based magnets were first realized through the synthesis and study of [bis(pentamethylcyclopentadienyl)iron(III)] + [tetracyanoethenide] − , [Fe III Cp 2 *] •+ [TCNE] •– , 1 , which magnetically orders below its ordering or critical temperature, T c , of 4.8 K. − Ordering as a ferromagnet was ascertained from the saturation magnetization and magnetic structure elucidated from neutron diffraction studies . The discovery of ferromagnetic ordering in an organic-based magnet (OBM) has been of significant importance to theoretical solid-state physics and shows potential for accessing multifunctional materials. − [FeCp 2 *] •+ [TCNE] −• is an electron transfer salt possessing parallel linear chains of alternating S = 1/2[FeCp 2 *] •+ cations and S = 1/2[TCNE] •– anions, with and without solvent. , Several [M III Cp 2 *] + [A] •– analogs have been synthesized through the variation of the paramagnetic metal center (M = Fe, Mn, Cr) and/or the cyanocarbon electron acceptor [A = TCNE, 7,7,8,8-tetracyano- p -quinodimethane (TCNQ), hexacyanobutadiene (HCBD), 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ), and 2,3-dicyano-1,4-naphthoquinonide (DCNQ)] .…”

Average g-Factors of Anisotropic Polycrystalline Samples

“…The inequality g av CW > g av sat is satisfied in six of eight cases, including for the three-dimensional compound [Fe(C 5 Me 5 ) 2 ] 4 [HFeW 12 O 40 ] . Notice that g av sat / g av CW lies between 0.92 and 0.95 for two polycrystalline samples containing the spin-1/2 TCNE − anion, one primarily aligned along the field direction and the other primarily aligned in the plane perpendicular to the field.…”

“…For the average Curie constant and saturation magnetization where the anion is assumed to be isotropic. Recall that C av (cation) ∝ (g av CW ) 2 7 Notice that g av sat /g av CW lies between 0.92 and 0.95 for two polycrystalline samples containing the spin-1/2 TCNEanion, 9 one primarily aligned along the field direction and the other primarily aligned in the plane perpendicular to the field.…”