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Papánková, B.; Vrbová, Martina; Boča, Roman; Šimon, Peter; Falk, Karsten; Miehe, G.; Fueß, H.

doi:10.1023/a:1014377410046

Cited by 19 publications

(15 citation statements)

References 13 publications

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“…From these values and the temperature for the heat flow maxima ( Tc ), the value of Δ S was calculated according to Δ S = Δ H/T c , resulting, in J/mol, Δ S cooling = 46.90, and Δ S heating = 40.10. As expected, the obtained values of Δ H and Δ S for the two processes are quite similar but, quite different to the ones reported for other ferrous materials where the spin crossover has been reported, particularly, to the values of Δ H , which are above 15 kJ/mol , , . These low values for Δ H are in correspondence with the small structural changes related to the spin transition, with a unit cell volume variation of only 0.7 % and a change for the Fe–N Py distance of 0.10 Å (discussed above).…”

Section: Resultssupporting

confidence: 60%

Thermally Induced Spin Transition in a 2D Ferrous Nitroprusside

et al. 2019

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This study reports the intercalation of pyridine molecules between neighboring layers of two-dimensional (2D) ferrous nitroprusside. In the material under study, the stacking of neighboring layers results in the formation of a long range ordered solid, where the 3D structure is supported by dipoledipole attractive interactions between neighboring pyridine molecules in the interlayer region. No chemical interactions were observed between layers, which preserve their identity as a 2D material. In this hybrid inorganic-organic solid, a thermal induced spin transitions from high to low spin on cooling and [a] 4967 [a] The values of δ are reported relative to sodium nitroprusside at 300 K; The fitting error for δ and Δ is no higher than 0.001 mm/s, and it remains below 0.01 mm/s for the value of Γ; Py =pyridine; LS = low spin; HS = high spin.

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Section: Resultssupporting

confidence: 60%

Thermally Induced Spin Transition in a 2D Ferrous Nitroprusside

et al. 2019

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“…On further heating (path-6), the system turns to the high-spin with the saturation effective magnetic moment of l eff = 4.0 l B at 480 K. The second cooling (path-7) copies exactly the first cooling (path-3). High value of DH = 18 kJ mol À1 and moderate DS = 43 J K À1 mol À1 determine a high value of T c = DH/ DS = 424 matching the calorimetric readings T " p1 ¼ 424 [18]. Since the second heating and cooling paths are different, a ''broad hysteresis'' is visible between 300 and 500 K for 4b.…”

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confidence: 69%

“…The effective magnetic moment rises from its room-temperature value l eff = 1.8 l B -4.2 l B at the limit of the heating (500 K) where 4 turns to 4b. There are irreversible changes between T = 503 and 523 K: the liberation of the crystal water, the color change (blue-green) followed by a structure change as determined by the TG analysis, IR spectra, and X-ray powder diffraction [18]. The first cooling path-3 for 4b has a different profile than the heating path-2 for 4.…”

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confidence: 99%

Tuning the spin crossover above room temperature: iron(II) complexes of substituted and deprotonated 2,6-bis(benzimidazol-2-yl)pyridine

Boča

Renz

Boča

et al. 2005

Inorganic Chemistry Communications

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“…-Mepy)2(py)tren] 2+ , 44 8: [Fe(tppn)] 2+ , 45 9: [Fe(tpchxn)] 2+ , 45 10: [Fe(ppa)2] 2+ , 45 11: [Fe(phen)2(NCS)2] 46 and its selenocyanate analog 12: [Fe(phen)2(NCSe)2], 46 13: [Fe(2-pic)3] 2+ , 46 14: [Fe(bt)2(NCS)2], 47 15: [Fe(bzimpy)2], 48 16:…”

Section: Methodsmentioning

confidence: 99%

Theoretical Study of Spin Crossover in 30 Iron Complexes

2016

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Iron complexes are important spin crossover (SCO) systems with vital roles in oxidative metabolism and promising technological potential. The SCO tendency depends on the free energy balance of high- and low-spin states, which again depends on physical effects such as dispersion, relativistic effects, and vibrational entropy. This work studied 30 different iron SCO systems with experimentally known thermochemical data, using 12 different density functionals. Remarkably general entropy-enthalpy compensation across SCO systems was identified (R = 0.82, p = 0.002) that should be considered in rational SCO design. Iron(II) complexes displayed higher ΔH and ΔS values than iron(III) complexes and also less steep compensation effects. First-coordination sphere ΔS values computed from numerical frequencies reproduce most of the experimental entropy and should thus be included when modeling spin-state changes in inorganic chemistry (R = 0.52, p = 3.4 × 10(-3); standard error in TΔS ≈ 4.4 kJ/mol at 298 K vs 16 kJ/mol of total TΔS on average). Zero-point energies favored high-spin states by 9 kJ/mol on average. Interestingly, dispersion effects are surprisingly large for the SCO process (average: 9 kJ/mol, but up to 33 kJ/mol) and favor the more compact low-spin state. Relativistic effects favor low-spin by ∼9 kJ/mol on average, but up to 24 kJ/mol. B3LYP*, TPSSh, B2PLYP, and PW6B95 performed best for the typical calculation scheme that includes ZPE. However, if relativistic and dispersion effects are included, only B3LYP* remained accurate. On average, high-spin was favored by LYP by 11-15 kJ/mol relative to other correlation functionals, and by 4.2 kJ/mol per 1% HF exchange in hybrids. 13% HF exchange was optimal without dispersion, and 15% was optimal with all effects included for these systems.

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Cited by 19 publications

References 13 publications

Thermally Induced Spin Transition in a 2D Ferrous Nitroprusside

Thermally Induced Spin Transition in a 2D Ferrous Nitroprusside

Tuning the spin crossover above room temperature: iron(II) complexes of substituted and deprotonated 2,6-bis(benzimidazol-2-yl)pyridine

Theoretical Study of Spin Crossover in 30 Iron Complexes

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