Experimental

Gütlich, Philipp; Bill, Eckhard; Trautwein, Alfred X.

doi:10.1007/978-3-540-88428-6_3

Cited by 9 publications

(15 citation statements)

References 44 publications

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“…The value of a is only slightly larger than the natural linewidth nat = 0.385 mm s −1 [19], as expected. Similarly to what has been found for other metallic systems [17,30], the values of δ and V zz are essentially equal to zero. In terms of the Debye approximation for the lattice vibrations, the absorber Debye-Waller factor f a is expressed [16,17] by the Debye temperature, D , as…”

Section: Mössbauer Spectroscopysupporting

confidence: 83%

“…The 61 Ni ME measurements were conducted using a standard Mössbauer spectrometer operating in sine mode, using the 67.4 keV transition in 61 Ni [16,17]. Both the source and the absorber were in direct contact with liquid helium in a cryostat.…”

Section: Methodsmentioning

confidence: 99%

“…The measured 61 Ni Mössbauer spectrum was analyzed by means of a least-squares fitting procedure which entailed calculations of the positions and relative intensities of the absorption lines by numerical diagonalization of the full hyperfine interaction Hamiltonian. In the principal axis system of the electric field gradient (EFG) tensor, the Hamiltonian can be written as [16,17]…”

Section: Methodsmentioning

confidence: 99%

“…There is no firmly established relationship between the measured H hf and μ Ni . There are two major contributions to H hf at the nuclei of TM elements in metallic alloys [16,17]: the core contribution, due to the polarization of core s electrons and the polarization of the conduction electrons by the 3d electrons (i.e., by the on-site magnetic moment), and the conduction electron contribution, due to the polarization of the conduction electrons by the surrounding magnetic moments. The first contribution is proportional to the local magnetic moment μ l , whereas the second contribution is assumed to be proportional to the average moment per magnetic atom μ TM Thus, a phenomenological relation is used [31] H hf = aμ l + bμ TM ,…”

Section: Mössbauer Spectroscopymentioning

confidence: 99%

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Magnetic properties and⁶¹Ni Mössbauer spectroscopy of the ternary phosphide CrNiP

Stadnik

Wang

Jansen

et al. 2008

J. Phys.: Condens. Matter

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The results of x-ray diffraction, dc magnetization, and 61 Ni Mössbauer spectroscopy studies of the ternary phosphide CrNiP are reported. This compound crystallizes in the orthorhombic Co 2 P-type structure (space group Pnma) with the lattice parameters a = 5.7965(1) Å, b = 3.5337(1) Å, and c = 6.8123(2) Å. NiCrP is a ferromagnet with Curie temperature T C = 135.1(1) K. The ferromagnetic-to-paramagnetic transition is characterized by the critical exponents β = 0.355(22), γ = 1.241(18), and δ = 4.585 (20). Their values are close to those of a 3D Heisenberg ferromagnet. The temperature dependence of the magnetic susceptibility above T C follows the modified Curie-Weiss law with a paramagnetic Curie temperature of 142.9(6) K and effective magnetic moment per transition-metal atom of 1.70(2) μ B . The magnetic moment per formula unit at 4.2 K is found to be 0.816(13) μ B . The hyperfine magnetic field at 61 Ni nuclei at 4.2 K of 32.3(1.3) kOe implies that the Ni atoms carry a magnetic moment of 0.14(8) μ B , and that the moment carried by the Cr atoms is 0.68(9) μ B . The Debye temperature of NiCrP is 261(3) K.

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Section: Mössbauer Spectroscopysupporting

confidence: 83%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Mössbauer Spectroscopymentioning

confidence: 99%

See 2 more Smart Citations

Magnetic properties and⁶¹Ni Mössbauer spectroscopy of the ternary phosphide CrNiP

Stadnik

Wang

Jansen

et al. 2008

J. Phys.: Condens. Matter

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“…In both cases, the quadrupole splitting is larger than in the parent PcFe (which has a small dependency on the solid-state phase of this compound). In the simplistic point-charge model, Mössbauer quadrupole splitting can be calculated as sums of valence and lattice contributions according to eqs and , respectively. , where ⟨ r –3 ⟩ 3d and ⟨ r –3 ⟩ 4p are the expectation values of 1/ r 3 taken over the appropriate 3d and 4p radial functions at the iron atom, respectively. The terms (1 – R ) and (1 – γ ∞ ) are constants, and n is an effective population of the atomic orbitals designated by parentheses.…”

Section: Resultsmentioning

confidence: 99%

Resolving a Half-Century-Long Controversy between (Magneto)optical and EPR Spectra of Single-Electron-Reduced [PcFe]⁻, [PcFeL]⁻, and [PcFeX]^2– Complexes: Story of a Double Flip

et al. 2022

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The reduction of iron(II) phthalocyanine (Pc(2−)FeII) or its bisaxially coordinated complexes results in the formation of the purple/red [PcFe]−, [PcFeL]−, and [PcFeX]2– (L is neutral and X is anionic ligand) species. The X-ray structure of the [K(DME)4][PcFe] complex exhibits a square-planar [PcFe]− anion. 1H NMR spectra of the reduced species have one or two phthalocyanine broad peaks between 15 and 17 ppm. Solution magnetic moments are consistent with the presence of a single unpaired electron. A solid-state Mössbauer spectrum of [K(DME)4][PcFe] is consistent with an early report [Pure Appl. Chem.197438427438]. The solid-state EPR spectrum of the [PcFe]− anion is close to that recorded by Konarev et al. [Dalton Trans.2012411384113847]. Solution EPR spectra of reduced species have axial symmetry (g ⊥ ∼ 2.08–2.17 and g || ∼ 1.95–1.96) and correlate well with spectra reported by Lever and Wilshire in 1978 [Inorg. Chem.19781711451151]. The UV–vis spectra of pentacoordinated [PcFeL]− and [PcFeX]2– anions consist of the characteristic bands around 810, 690, and 515 nm. These bands correlate well with the set of MCD pseudo A-terms and resemble transitions in the [Pc(3−)M]− and [Pc(3−)ML]− compounds. The UV–vis and MCD spectra of [PcFeL]− and [PcFeX]2– complexes are in stark contrast to the crystallographically characterized reference [Pc(2−)CoI]− anion, which is EPR silent, has a regular diamagnetic 1H NMR spectrum, and has an intense Q-band at 699 nm, which correlates well with the strong MCD A-term. The DFT and TDDFT calculations are suggestive of the iron(II) center in a (d xy )2(d xz , yz )3(d z 2 )1 (s = 1) electronic configuration that is antiferromagnetically coupled with the one-electron-reduced Pc(3−) ligand (i.e., [Pc(3−)FeII]−, [Pc(3−)FeIIL]−, and [Pc(3−)FeIIX]2–). The calculated EPR, Mössbauer, and UV–vis spectra of [PcFe]−, [PcFeL]−, and [PcFeX]2– complexes are in excellent agreement with the experimental data, thus resolving the controversy between axial s = 1/2 like EPR and Pc(3−)-like UV–vis spectra of these compounds.

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How Rigidity and Conjugation of Bidentate Ligands Affect the Geometry and Photophysics of Iron N-Heterocyclic Complexes: A Comparative Study

Prakash,

Chábera,

Kaul

et al. 2024

Inorg. Chem.

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Two iron complexes featuring the bidentate, nonconjugated Nheterocyclic carbene (NHC) 1,1′-methylenebis(3-methylimidazol-2-ylidene) (mbmi) ligand, where the two NHC moieties are separated by a methylene bridge, have been synthesized to exploit the combined influence of geometric and electronic effects on the ground-and excited-state properties of homoleptic Fe IIIhexa-NHC [Fe(mbmi) 3 ](PF 6 ) 3 and heteroleptic Fe II -tetra-NHC [Fe-(mbmi) 2 (bpy)](PF 6 ) 2 (bpy = 2,2′-bipyridine) complexes. They are compared to the reported Fe III -hexa-NHC [Fe(btz) 3 ](PF 6 ) 3 and Fe II -tetra-NHC [Fe-(btz) 2 (bpy)](PF 6 ) 2 complexes containing the conjugated, bidentate mesoionic NHC ligand 3,3′-dimethyl-1,1′-bis(p-tolyl)-4,4′-bis(1,2,3-triazol-5-ylidene) (btz). The observed geometries of [Fe(mbmi) 3 ](PF 6 ) 3 and [Fe(mbmi) 2 (bpy)](PF 6 ) 2 are evaluated through L−Fe−L bond angles and ligand planarity and compared to those of [Fe(btz) 3 ](PF 6 ) 3 and [Fe(btz) 2 (bpy)](PF 6 ) 2 . The Fe II /Fe III redox couples of [Fe(mbmi) 3 ](PF 6 ) 3 (−0.38 V) and [Fe(mbmi) 2 (bpy)](PF 6 ) 2 (−0.057 V, both vs Fc +/0 ) are less reducing than [Fe(btz) 3 ](PF 6 ) 3 and [Fe(btz) 2 (bpy)](PF 6 ) 2 . The two complexes show intense absorption bands in the visible region: [Fe(mbmi) 3 ](PF 6 ) 3 at 502 nm (ligand-to-metal charge transfer, 2 LMCT) and [Fe(mbmi) 2 (bpy)](PF 6 ) 2 at 410 and 616 nm (metalto-ligand charge transfer, 3 MLCT). Lifetimes of 57.3 ps ( 2 LMCT) for [Fe(mbmi) 3 ](PF 6 ) 3 and 7.6 ps ( 3 MLCT) for [Fe(mbmi) 2 (bpy)](PF 6 ) 2 were probed and are somewhat shorter than those for [Fe(btz) 3 ](PF 6 ) 3 and [Fe(btz) 2 (bpy)](PF 6 ) 2 .[Fe(mbmi) 3 ](PF 6 ) 3 exhibits photoluminescence at 686 nm ( 2 LMCT) in acetonitrile at room temperature with a quantum yield of (1.2 ± 0.1) × 10 −4 , compared to (3 ± 0.5) × 10 −4 for [Fe(btz) 3 ](PF 6 ) 3 .

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Experimental

Cited by 9 publications

References 44 publications

Magnetic properties and⁶¹Ni Mössbauer spectroscopy of the ternary phosphide CrNiP

Magnetic properties and⁶¹Ni Mössbauer spectroscopy of the ternary phosphide CrNiP

Resolving a Half-Century-Long Controversy between (Magneto)optical and EPR Spectra of Single-Electron-Reduced [PcFe]⁻, [PcFeL]⁻, and [PcFeX]^2– Complexes: Story of a Double Flip

How Rigidity and Conjugation of Bidentate Ligands Affect the Geometry and Photophysics of Iron N-Heterocyclic Complexes: A Comparative Study

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Experimental

Cited by 9 publications

References 44 publications

Magnetic properties and61Ni Mössbauer spectroscopy of the ternary phosphide CrNiP

Magnetic properties and61Ni Mössbauer spectroscopy of the ternary phosphide CrNiP

Resolving a Half-Century-Long Controversy between (Magneto)optical and EPR Spectra of Single-Electron-Reduced [PcFe]−, [PcFeL]−, and [PcFeX]2– Complexes: Story of a Double Flip

How Rigidity and Conjugation of Bidentate Ligands Affect the Geometry and Photophysics of Iron N-Heterocyclic Complexes: A Comparative Study

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Magnetic properties and⁶¹Ni Mössbauer spectroscopy of the ternary phosphide CrNiP

Magnetic properties and⁶¹Ni Mössbauer spectroscopy of the ternary phosphide CrNiP

Resolving a Half-Century-Long Controversy between (Magneto)optical and EPR Spectra of Single-Electron-Reduced [PcFe]⁻, [PcFeL]⁻, and [PcFeX]^2– Complexes: Story of a Double Flip