Mössbauer spectra, structure, and bonding in iron carbonyl derivatives

Greatrex, Robert; Greenwood, N. N.

doi:10.1039/df9694700126

Cited by 57 publications

(42 citation statements)

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“…An interesting result is that the magnitude of this effect seems to be rather independent of the computational method applied. Structural effects can be obtained by comparing the different EFGs at the B3LYP level in different geometries ͑in a.u.͒: PAW geometry 26 we obtain a final NQM of Q ϭϩ0.12 b. This would support the value derived by Su and Coppens.…”

Section: A Fe"co…supporting

confidence: 81%

Comparison of ab initio and density functional calculations of electric field gradients: The Fe57 nuclear quadrupole moment from Mössbauer data

Schwerdtfeger

Söhnel

Pernpointner

et al. 2001

The Journal of Chemical Physics

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Articles you may be interested inThe nuclear electric quadrupole moment of antimony from the molecular methodThe quadrupole moment of the 3 ∕ 2 + nuclear ground state of Au 197 from electric field gradient relativistic coupled cluster and density-functional theory of small molecules and the solid state A point-charge model for the nuclear quadrupole moment: Coupled-cluster, Dirac-Fock, Douglas-Kroll, and nonrelativistic Hartree-Fock calculations for the Cu and F electric field gradients in CuFThe difficulty in accurate determination of the nuclear quadrupole moment of the first Iϭ3/2 excited nuclear state of 57 Fe from electronic structure calculations of the iron electric field gradient combined with Mössbauer measurements of the nuclear quadrupole splitting in the isomer shift is addressed by comparing ab initio with density functional calculations for iron pentacarbonyl, Fe͑CO͒ 5 , ferrocene, Fe͑C 5 H 5 ͒ 2 , and the 5 ⌬ g electronic ground states of FeCl 2 and FeBr 2 . While the ligand field gradient tensor components change relatively little with the method applied, the iron electric field gradient is sensitive to the specific density functional used. Single reference many-body perturbation theory for electron correlation also performs poorly for the iron electric field gradient and shows extreme oscillatory behavior with a change in the order of the perturbation series. Even with larger basis sets and coupled cluster techniques a precise value for the iron electric field gradient could not be determined from electronic structure calculations due to limitations in the theoretical procedures. In order to avoid uncertainties in the measured isomer shift which enters into the nuclear quadrupole coupling constant we determined the Mössbauer spectrum of Fe͑C 5 H 5 ͒ 2 between temperatures of 4.2 and 295 K. In this range two phase transitions are observed, but the quadrupole splitting is not very dependent on the solid state structure in each phase. Solid state effects for the Fe͑CO͒ 5 are determined by comparing the iron electric field gradient of the isolated molecule with the value obtained from first principle solid state calculations at various levels of theory. These calculations show that the influence of near neighboring effects to the iron electric field gradient is small. Fully relativistic Dirac-Hartree-Fock calculations for Fe͑CO͒ 5 reveal that relativistic effects for the iron electric field gradient are small as well. Fe͑CO͒ 5 is therefore an ideal test molecule for the determination of an accurate nuclear quadrupole moment from electronic structure calculations if combined with an experimental nuclear quadrupole coupling constant. Our best estimate for the 57 Fe nuclear quadropole moment is 0.14͑2͒ barn in reasonable agreement with recent nuclear structure calculations.

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Section: A Fe"co…supporting

confidence: 81%

Comparison of ab initio and density functional calculations of electric field gradients: The Fe57 nuclear quadrupole moment from Mössbauer data

Schwerdtfeger

Söhnel

Pernpointner

et al. 2001

The Journal of Chemical Physics

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“…In this case the Mössbauer spectrum is expected to show two different types of resonance signals with intensity ratio of 2:1. The measured Mössbauer spectrum of Fe 3 (CO) 12 [35] (right) shows two types of resonance signals, A and B, and confirms that the structure with two types of iron positions is the correct one. and rhombically distorted, which leads to nonzero EFG and the observed quadrupole splitting in the Mössbauer spectrum.…”

Section: Molecular Symmetry -Information From Quadrupole Splittingsupporting

confidence: 57%

“…In this case the Mössbauer spectrum is expected to show two different types of resonance signals with an area ratio of 2:1. A Mössbauer effect study performed by Greatrex and Greenwood in 1969 [35] indeed showed two types of resonance signals, a quadrupole doublet A and a singlet B with an area ratio of 2:1 confirming the presence of two types of iron positions in Fe 3 (CO) 12 (Figure 15).…”

Section: Molecular Symmetry -Information From Quadrupole Splittingmentioning

confidence: 84%

Fifty Years of Mössbauer Spectroscopy in Solid State Research – Remarkable Achievements, Future Perspectives

Gütlich

2011

Zeitschrift anorg allge chemie

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Mössbauer spectroscopy was founded more than fifty years ago based on an outstanding discovery by the young German physicist Rudolf Ludwig Mössbauer while working on his Ph.D. thesis. He discovered the recoilless nuclear resonance fluorescence of gamma radiation and was awarded the Nobel Prize in Physics in 1961 as one of the youngest recipients of this most prestigious award. His discovery 15 led to the development of a new technique for measurements of hyperfine interactions between nuclear moments and electromagnetic fields. This method, with highest sharpness of tuning of 10 -13 , yields information on valence state, symmetry, magnetic behavior, phase transition, lattice dynamics and other solid state properties.

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“…Curiously Zhang et al cite the same experimental paper for their value of À0.18 mm s À1 , as do Kurian and Filatov 25 who report À0.140 mm s À1 . More recent experimental isomer shifts for Fe(CO) 5 are reported by Greatrex and Greenwood75 and Kuhn et al76 who report +0.17 mm s À1 (77 K) and +0.18 mm s À1 (113 K), respectively, both using hydrated sodium nitroprusside at room temperature as reference, which translates into À0.088 mm s À1 and À0.078 mm s À1 relative to a-Fe foil. Finally, for completeness, a Mo ¨ssbauer isomer shift of À0.174 mm s À1 is reported by De Paoli et al77 at 4.2 K for Fe(CO) 5…”

mentioning

confidence: 84%

Theoretical ⁵⁷Fe Mössbauer spectroscopy: isomer shifts of [Fe]-hydrogenase intermediates

Hedegård

Knecht

Ryde

et al. 2014

Phys. Chem. Chem. Phys.

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Mössbauer spectroscopy is an indispensable technique and analytical tool in iron coordination chemistry. The linear correlation between the electron density at the nucleus ("contact density") and experimental isomer shifts has been used to link calculated contact densities to experimental isomer shifts. Here we have investigated for the first time relativistic methods of systematically increasing sophistication, including the eXact 2-Component (X2C) Hamiltonian and a finite-nucleus model, for the calculation of isomer shifts for iron compounds.While being of similar accuracy as the full four-component treatment, X2C calculations are far more efficient. We find that effects from spin orbit coupling can safely be neglected, leading to further speed up. Linear correlation plots using effective densities rather than contact densities versus experimental isomer shift leads to a correlation constant a = −0.32 a −3 0 mm s −1 (PBE functional) which is in close agreement to experimental findings. Isomer shifts of similar quality can thus be obtained both with and without fitting, which is not the case if one pursues a priori a non-relativistic model approach. As an application for a biologically relevant system, we have studied three recently proposed [Fe]-hydrogenase intermediates. The structures for these intermediates were extracted from QM/MM calculations using large QM regions surrounded by the full enzyme and a solvation shell of water molecules. We show that a comparison between calculated and experimentally observed isomer shifts can be used to discriminate between the different intermediates, whereas calculated atomic charges do not necessarily correlate with Mössbauer isomer shifts. Detailed analysis shows that the difference in isomer shifts between two intermediates is due to an overlap effect.

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Mössbauer spectra, structure, and bonding in iron carbonyl derivatives

Cited by 57 publications

References 1 publication

Comparison of ab initio and density functional calculations of electric field gradients: The Fe57 nuclear quadrupole moment from Mössbauer data

Comparison of ab initio and density functional calculations of electric field gradients: The Fe57 nuclear quadrupole moment from Mössbauer data

Fifty Years of Mössbauer Spectroscopy in Solid State Research – Remarkable Achievements, Future Perspectives

Theoretical ⁵⁷Fe Mössbauer spectroscopy: isomer shifts of [Fe]-hydrogenase intermediates

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Mössbauer spectra, structure, and bonding in iron carbonyl derivatives

Cited by 57 publications

References 1 publication

Comparison of ab initio and density functional calculations of electric field gradients: The Fe57 nuclear quadrupole moment from Mössbauer data

Comparison of ab initio and density functional calculations of electric field gradients: The Fe57 nuclear quadrupole moment from Mössbauer data

Fifty Years of Mössbauer Spectroscopy in Solid State Research – Remarkable Achievements, Future Perspectives

Theoretical 57Fe Mössbauer spectroscopy: isomer shifts of [Fe]-hydrogenase intermediates

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Theoretical ⁵⁷Fe Mössbauer spectroscopy: isomer shifts of [Fe]-hydrogenase intermediates