Free Energy of Spin-Crossover Complexes Calculated with Density Functional Methods

Paulsen, Hauke; Duelund, Lars; Winkler, H.; Toftlund, and Hans; Trautwein, Alfred X.

doi:10.1021/ic000954q

Cited by 284 publications

(230 citation statements)

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“…In contrast Paulsen et al [49] also showed that the HS state is stabilised with respect to the LS state and is falsely predicted to be the ground state if the B3LYP functional is used. This functional is the workhorse of the hybrid-XC energy functionals.…”

Section: Dft Characterisation Of Ls and Hs States Of Iron(ii) Complexesmentioning

confidence: 93%

“…Thus, Paulsen et al [49] noticed that commonly used GGAs-namely, the BLYP functional which combines Becke's 1988 (B or B88) exchange GGA [50] and the Lee-Yang-Parr (LYP) correlation GGA, [51] as well as the PW91 exchange-correlation GGA of Perdew and Wang [52][53][54][55] -give the expected LS ground state for the investigated iron(II) spin-crossover complexes, but they tend to give too high DE el:…”

Section: Dft Characterisation Of Ls and Hs States Of Iron(ii) Complexesmentioning

confidence: 99%

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Assessment of Density Functionals for the High‐Spin/Low‐Spin Energy Difference in the Low‐Spin Iron(II) Tris(2,2′‐bipyridine) Complex

et al. 2005

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In the iron(II) low‐spin complex [Fe(bpy)3]2+, the zero‐point energy difference between the 5T2g(t${{{4\hfill \atop 2g\hfill}}}$${e{{2\hfill \atop g\hfill}}}$) high‐spin and the 1A1g(t${{{6\hfill \atop 2g\hfill}}}$) low‐spin states, ΔE${{{0\hfill \atop HL\hfill}}}$, is estimated to lie in the range of 2500–5000 cm−1. This estimate is based on the low‐temperature dynamics of the high‐spin→low‐spin relaxation following the light‐induced population of the high‐spin state and on the assumption that the bond‐length difference between the two states ΔrHL is equal to the average value of ≈0.2 Å, as found experimentally for the spin‐crossover system. Calculations based on density functional theory (DFT) validate the structural assumption insofar as the low‐spin‐state optimised geometries are found to be in very good agreement with the experimental X‐ray structure of the complex and the predicted high‐spin geometries are all very close to one another for a whole series of common GGA (PB86, PW91, PBE, RPBE) and hybrid (B3LYP, B3LYP*, PBE1PBE) functionals. This confirmation of the structural assumption underlying the estimation of ΔE${{{0\hfill \atop HL\hfill}}}$ from experimental relaxation rate constants permits us to use this value to assess the ability of the density functionals for the calculation of the energy difference between the HS and LS states. Since the different functionals give values from −1000 to 12000 cm−1, the comparison of the calculated values with the experimental estimate thus provides a stringent criterion for the performance of a given functional. Based on this comparison the RPBE and B3LYP* functionals give the best agreement with experiment.

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Section: Dft Characterisation Of Ls and Hs States Of Iron(ii) Complexesmentioning

confidence: 93%

Section: Dft Characterisation Of Ls and Hs States Of Iron(ii) Complexesmentioning

confidence: 99%

Assessment of Density Functionals for the High‐Spin/Low‐Spin Energy Difference in the Low‐Spin Iron(II) Tris(2,2′‐bipyridine) Complex

et al. 2005

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“…Probably one of the first papers to describe the sensitivity of the spin ground-state of transition metal complexes was a study by Trautwein and coworkers [2] in 2001, who showed for the first time the intrinsic spin-state preferences of hybrid functionals such as B3LYP (for high spin) and early generalized gradient approximations (GGA) functionals like BLYP/BP86 (for low spin). Since then new density functionals were proposed (B3LYP*, OPBE/OLYP, TPSSh, M06-L, SSB-D) that were shown to perform better (see e.g., Refs.…”

Section: Advances In Methodologymentioning

confidence: 99%

“…As mentioned above, Trautwein and coworkers [2] reported in 2001 a study on SCO compounds, which were studied with different density functionals. Since then there have been many more studies into the SCO phenomenon, which can be induced by changes in temperature, pressure, and so forth.…”

Section: Spin-crossover Compoundsmentioning

confidence: 98%

“…[31] Interestingly enough, substitution patterns at the pyrazolyl rings influence the SCO-behavior dramatically, and for the T c ligands, there was in some cases a dramatic effect of the counter-ion. [31] For example, whereas the parent compounds Fe(T b ) 2 and Fe(T c ) 2 2þ showed transition temperatures for the low-spin to high-spin switch above room temperature, placing a methyl group at the 3-position leads directly to high spin at low temperatures; instead, placing a methyl group at the 4-or 5-position has hardly an effect. We studied these complexes as well, [31] at the OPBE/TZP level, [32] and found that in general there was good agreement between the computed spin-state splittings at 0 K and the experimentally observed (or absent) SCO-behavior.…”

Section: Spin-crossover Compoundsmentioning

confidence: 99%

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Spin states of (bio)inorganic systems: Successes and pitfalls

Swart

2012

Int J of Quantum Chemistry

112

127

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The calculation of spin-state splittings of transition-metal complexes is known to be very sensitive to the level of theory and the quality of the basis set. The performance of density functionals is in general understood, with older pure functionals overstabilizing low spin states, and Hartree-Fock and hybrid functionals doing the same for the high spin states. More recent functionals (OLYP/OPBE, TPSSh, SSB-D, M06-L) seem to improve on these, but there are still some systems that prove difficult. This Perspective describes some of the recent successes and pitfalls in the description of spin states and treats both methodology and applications such as metal-oxo complexes, exchange-enhanced reactivity, spin-state catalysis, and spin-crossover compounds.

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Iron: Inorganic & Coordination ChemistryBased in part on the article Iron: Inorganic & Coordination Chemistry by Pelham N. Hawker & Martyn V. Twigg which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.

Burgess

Twigg

2005

Encyclopedia of Inorganic Chemistry

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Iron, the most abundant transition element in the biosphere, is essential in higher forms of life and its compounds have numerous industrial applications. The element has catalytic properties. Several simple iron compounds are industrially important, for example, large amounts of iron oxides are produced for pigment and magnetic recording media applications. Oxidation states ranging from −2 to +6 are known, the most familiar are +2 (ferrous iron) and +3 (ferric iron). Most common complexes are octahedral, although examples of higher (e.g. seven coordinate) and lower (e.g. tetrahedral and square planar) geometries are well known, as are a variety of mixed oxidation state compounds. Depending on ligands involved high‐ and low‐spin complexes can be formed, and temperature‐dependent spin‐state crossover complexes are well documented. The thermodynamics and kinetics of reactions of low‐spin iron(II) complexes with ligands such as 1,4‐diimines and CN − have been extensively studied. While low‐spin iron(II) is present in biological systems such as oxygenated heme centered oxygen carriers and thiolate clusters, iron(III) is more common. Thiolate‐containing iron clusters form readily, and here mixed oxidation states are a prominent feature that is exploited in some important electron transfer proteins. Microorganism iron uptake is facilitated by tris‐catecholate and tris‐hydroxamate ligands like enterobactin that have an extraordinarily high affinity for iron(III) that results in a dramatic enhancement of the 3+ relative to the 2+ state in terms of redox potential.

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Free Energy of Spin-Crossover Complexes Calculated with Density Functional Methods

Cited by 284 publications

References 21 publications

Assessment of Density Functionals for the High‐Spin/Low‐Spin Energy Difference in the Low‐Spin Iron(II) Tris(2,2′‐bipyridine) Complex

Assessment of Density Functionals for the High‐Spin/Low‐Spin Energy Difference in the Low‐Spin Iron(II) Tris(2,2′‐bipyridine) Complex

Spin states of (bio)inorganic systems: Successes and pitfalls

Iron: Inorganic & Coordination ChemistryBased in part on the article Iron: Inorganic & Coordination Chemistry by Pelham N. Hawker & Martyn V. Twigg which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.

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