Electron-transfer transitions in hexachloroferrate(III). Single-crystal absorption and MCD spectra

Neuenschwander, K.; Guedel, Hans U.; Collingwood, J.C.; Schatz, P. N.

doi:10.1021/ic00154a004

Cited by 14 publications

(4 citation statements)

References 8 publications

(15 reference statements)

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“…The trends observed in the experimental spectra are generally reproduced in the simulations. The simulated spectra match the experiment within the first ∼2.5 eV; at higher transition energies there are also CT contributions to the RIXS spectra, consistent with previous MCD results of Neuenschwander et al 43 Previous studies have shown that multiplet calculations can reproduce ligand field spectra with reasonable accuracy. 15,44 In addition to providing spectral profiles to correlate the simulated and experimental data, the simulations yield a fully diagonalized ligand field Hamiltonian.…”

Section: ■ Resultssupporting

confidence: 88%

Measurement of the Ligand Field Spectra of Ferrous and Ferric Iron Chlorides Using 2p3d RIXS

et al. 2017

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Ligand field spectra provide direct information about the electronic structure of transition metal complexes. However, these spectra are difficult to measure by conventional optical techniques due to small cross sections for d-to-d transitions and instrumental limitations below 4000 cm. 2p3d resonant inelastic X-ray scattering (RIXS) is a second order process that utilizes dipole allowed 2p to 3d transitions to access d-d excited states. The measurement of ligand field excitation spectra by RIXS is demonstrated for a series of tetrahedral and octahedral Fe(II) and Fe(III) chlorides, which are denoted Fe(III)-T, Fe(II)-T, Fe(III)-O, and Fe(II)-O. The strong 2p spin-orbit coupling allows the measurement of spin forbidden transitions in RIXS spectroscopy. The Fe(III) spectra are dominated by transitions from the sextet ground state to quartet excited states, and the Fe(II) spectra contain transitions to triplet states in addition to the spin allowed Γ →Γ transition. Each experimental spectrum is simulated using a ligand field multiplet model to extract the ligand field splitting parameter 10Dq and the Racah parameters B and C. The 10Dq values for Fe(III)-T, Fe(II)-T, and Fe(III)-O are found to be -0.7, -0.32, and 1.47 eV, respectively. In the case of Fe(II)-O, a single 10Dq parameter cannot be assigned because Fe(II)-O is a coordination polymer exhibiting axially compressed Fe(II)Cl units. TheT → E transition is split by the axial compression resulting in features at 0.51 and 0.88 eV. The present study forms the foundation for future applications of 2p3d RIXS to molecular iron sites in more complex systems, including iron-based catalysts and enzymes.

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Section: ■ Resultssupporting

confidence: 88%

Measurement of the Ligand Field Spectra of Ferrous and Ferric Iron Chlorides Using 2p3d RIXS

et al. 2017

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“…Sometimes, the impurity replaces a host lattice ion keeping the local symmetry at least in the electronic ground state. This situation where only a symmetric distortion of neighbour ions happens is just found for divalent impurities like Ni 2+ or Mn 2+ in a cubic fluoroperovskite [15][16][17][18][19][20], or for Cr 3+ -or Fe 3+ -doped elpasolites [21][22][23][24][25][26][27][28][29][30]. However, there are other cases where the impurity remains on-centre in the electronic ground state but there is a non-symmetric distortion of neighbour ions leading to a reduction of the local symmetry.…”

Section: Introductionmentioning

confidence: 81%

“…By the same reason CT transitions are significantly red shifted along the series MF N → MCl N → MBr N . The onset of CT transitions of MX 4− 6 (M = Cu, Ag, Ni, Rh; X = Cl, Br) [142][143][144], CrCl 3− 6 [145] and FeCl 4− 6 [28] complexes lies in the optical region while that for CrF 3− 6 [146,147,26] and MnCl 4− 6 [142,143] complexes is at 64 000 and 58 000 cm −1 , respectively. A band peaked at 59 000 cm −1 in NaMgF 3 [148] can thus hardly be ascribed to a CT transition of an MnF 4− 6 complex, but it could arise from a 3d → 4s transition [149].…”

Section: Spectroscopic Parameters Of Impurity Centres With Cubic or T...mentioning

confidence: 99%

Microscopic insight into properties and electronic instabilities of impurities in cubic and lower symmetry insulators: the influence of pressure

Moreno

Barriuso

Aramburu

et al. 2006

J. Phys.: Condens. Matter

224

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This article reviews the microscopic origin of properties due to transition-metal (TM) impurities, M, in insulator materials. Particular attention is paid to the influence of pressure upon impurity properties. Basic concepts such as the electronic localization in an MX(N) complex, the electrostatic potential, V(R), arising from the rest of the lattice ions or the elastic coupling of the complex to the host lattice are initially exposed. The dependence of optical and magnetic parameters on the impurity-ligand distance, R, in cubic lattices is discussed in a first step. Emphasis is put on the actual origin of the R dependence of 10Dq. Examples revealing that laws for strict cubic symmetry cannot in general be transferred to lower symmetries are later given. This relevant fact is shown to come from allowed hybridizations like nd-(n+1)s as well as the influence of V(R). As a salient feature the different colour in ruby and emerald is stressed to arise from distinct V(R) potentials in Al(2)O(3) and Be(3)Si(6)Al(2)O(18). The last part of this review deals with electronic instabilities. The phenomena associated with the Jahn-Teller (JT) effect in cubic lattices, the origin of the energy barrier among equivalent minima and the existence of coherent tunnelling in systems like MgO:Cu(2+) are discussed. An increase of elastic coupling is pointed out to favour a transition from an elongated to a compressed equilibrium conformation. Interestingly the equilibrium geometry of JT ions in non-cubic lattices is shown to be controlled by mechanisms different to those in cubic systems, V(R) playing again a key role. The relevance of first principles calculations for clarifying the subtle mechanisms behind off-centre instabilities is also pointed out. Examples concern monovalent and divalent TM impurities in lattices with the CaF(2) structure. The instability due to the transition from the ground to an excited state is finally considered. For complexes with significant elastic coupling vibrational frequencies and the Stokes shift are expected to undergo bigger changes through a chemical rather than a hydrostatic pressure. The reduction of Huang-Rhys factors upon increasing the pressure is discussed as well.

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“…With the less electronegative chloride ion as the ligand a red shift of the CT‐bands is expected and observed. Thus, in the spectrum of Fe 3+ ‐doped Cs 2 NaY III Cl 6 , the transitions ν 1 extend into the visible region down to about 23000 cm –1 , lending a yellow hue to the crystal 1. The well‐resolved low‐intensity bands in the spectrum of NH 4 FeP 2 O 7 between 12 and 28 × 10 3 cm –1 are ligand field transitions and appear close in energy to those, observed for Fe(OH 2 ) 6 3+ ;2 they can be assigned and well reproduced in energy with a ligand field strength and electron repulsion parameters of Δ = 12350 cm –1 and B = 700 cm –1 , C/B = 4.9, respectively.…”

Section: The Spectral Properties Of Iron(iii) In Octahedral Hexaoximentioning

confidence: 96%

The Correlation between Structure and Color of Iron Oxide‐type Solids, Sustainable Pigments with Gentle Hues

Reinen

2014

Zeitschrift anorg allge chemie

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Oxidic solids with hexaccordinate iron(III) appear as colored species only, if charge-transfer bands are present in the visible region, which originate from transitions, occurring between low-lying mainly oxygen-centered electronic states and antibonding, predominantly metal-3d states. Transitions within the 3d-shell are expected to be only very weak in intensity, because they are not only parity-but also spinforbidden, and hence don't usually contribute signifycantly to the coloration. It is shown by various examples, how one may steer the hue by the aimed manipulation of certain structural and chemical parameters, which effectively alter the location and, in particular, the band-width of the charge transfer transitions. The spectral properties are compared with those of the isoelectronic hexaoxo-coordinate manganese(II). The subsequent discussion of the color properties of 3d 6 -

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Electron-transfer transitions in hexachloroferrate(III). Single-crystal absorption and MCD spectra

Cited by 14 publications

References 8 publications

Measurement of the Ligand Field Spectra of Ferrous and Ferric Iron Chlorides Using 2p3d RIXS

Measurement of the Ligand Field Spectra of Ferrous and Ferric Iron Chlorides Using 2p3d RIXS

Microscopic insight into properties and electronic instabilities of impurities in cubic and lower symmetry insulators: the influence of pressure

The Correlation between Structure and Color of Iron Oxide‐type Solids, Sustainable Pigments with Gentle Hues

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