Examination of <i>n</i>-beam interaction: X-ray experiment and simulation for KMnF<sub>3</sub>

Okazaki, Atsuo T.; Soejima, Yuji; Machida, Manabu; Ohe, Hiroshi

doi:10.1107/s0108768188008158

Cited by 6 publications

(1 citation statement)

References 8 publications

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“…Other contributions on MD and intensity corrections based on intensity transfer equations are e.g. Zachariasen (1965), Caticha-Ellis (1969), Prager (1971), Parente and Caticha-Ellis (1974), Le Page and Gabe (1979), Soejima et al (1985), Rossmanith (1986), Okazaki et al (1988) and Piltz (1988). Chang (1982) treated the intensity problem for n-beam diffraction in a dynamical formalism.…”

Section: Introductionmentioning

confidence: 99%

Correction of X-ray Intensities for Multiple Diffraction: Effects on Atomic Parameters and Charge Density

Hauback¹,

Mo²,

Thorkildsen³

1990

Aust. J. Phys.

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The standard theory for secondary extinction based on intensity transfer equations has been extended to three-beam diffraction for a finite crystal in the Laue case. The expression for the primary diffracted intensity was used to first order to calculate correction factors for the two-beam integrated power assuming a type I mosaic crystal. The corrections were employed to study the effects of multiple diffraction on structure parameters and deformation density for three different crystals with unit-cell volumes in the range 385-1410 A3. In these data sets, 5-8% of all reflections with (sinO/A) :S 0 -7 A-I had relative shifts in integrated power tl'P/'P> 10%. The weak intensities are affected the most, and thus, among the weakest third of the data, 15-21% had relative corrections >10%. The crystallographic Rand goodness-of-fit factors were significantly improved after correction of the data for multiple diffraction. Atomic positional and displacement parameters, obtained from the refinements on corrected and uncorrected data respectively, have been compared, as have also pairs of deformation density maps. Rather unexpectedly, all shifts were very small, within 20" for atomic parameters and within 2�50" for the deformation densities. This implies that the effects of multiple diffraction are nearly random relative to the structure model and even relative to the deformation density.

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Section: Introductionmentioning

confidence: 99%

Correction of X-ray Intensities for Multiple Diffraction: Effects on Atomic Parameters and Charge Density

Hauback¹,

Mo²,

Thorkildsen³

1990

Aust. J. Phys.

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Molecular Modeling of Dimetal Systems. Part 2. Low-Order Dimolybdenum

Boeyens

O'Neill

1998

Inorg. Chem.

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Through molecular modeling of the available structures containing dimolybdenum bonds of orders 3.5 and 3, solution pairs of harmonic force constant (k r) and bond length (r o) have been obtained as (3.63 mdyne/Å, 2.07 Å) and (3.37 mdyne/Å, 2.10 Å), respectively. Together with the known solution pair for MoMo, this sufficed to establish a general relationship between k r, r o and bond order, N, as N = 0.9537k r = 131.8r o -5. Using this relationship as a sampling curve, we extended the analysis to include Mo2 bonds of orders 2 and 1. The relationship was accordingly shown to apply to the entire {N, k r} space.

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[Re(η⁵-C₅H₅)(CO)₃]⁺ Family of 17-Electron Compounds: Monomer/Dimer Equilibria and Other Reactions

et al. 2008

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The anodic electrochemical oxidations of ReCp(CO)3 (1, Cp = eta(5)-C5H5), Re(eta(5)-C5H4NH2)(CO)3 (2), and ReCp*(CO)3 (3, Cp* = eta(5)-C5Me5), have been studied in CH2Cl2 containing [NBu4][TFAB] (TFAB = [B(C6F5)4]-) as supporting electrolyte. One-electron oxidations were observed with E(1/2) = 1.16, 0.79, and 0.91 V vs ferrocene for 1-3, respectively. In each case, rapid dimerization of the radical cation gave the dimer dication, [Re2Cp(gamma)2(CO)6]2+ (where Cp(gamma) represents a generic cyclopentadienyl ligand), which may be itself reduced cathodically back to the original 18-electron neutral complex ReCp(gamma)(CO)3. DFT calculations show that the SOMO of 1+ is highly Re-based and hybridized to point away from the metal, thereby facilitating the dimerization process and other reactions of the Re(II) center. The dimers, isolated in all three cases, have long metal-metal bonds that are unsupported by bridging ligands, the bond lengths being calculated as 3.229 A for [Re2Cp2(CO)6]2+ (1(2)2+) and measured as 3.1097 A for [Re2(C5H4NH2)2(CO)6]2+ (2(2)2+) by X-ray crystallography on [Re2(C5H4NH2)2(CO)6][TFAB]2. The monomer/dimer equilibrium constants are between K(dim) = 10(5) M(-1) and 10(7) M(-1) for these systems, so that partial dissociation of the dimers gives a modest amount of the corresponding monomer that is free to undergo radical cation reactions. The radical 1+ slowly abstracts a chlorine atom from dichloromethane to give the 18-electron complex [ReCp(CO)3Cl]+ as a side product. The radical cation 1+ acts as a powerful one-electron oxidant capable of effectively driving outer-sphere electron-transfer reactions with reagents having potentials of up to 0.9 V vs ferrocene.

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Examination of n-beam interaction: X-ray experiment and simulation for KMnF₃

Cited by 6 publications

References 8 publications

Correction of X-ray Intensities for Multiple Diffraction: Effects on Atomic Parameters and Charge Density

Correction of X-ray Intensities for Multiple Diffraction: Effects on Atomic Parameters and Charge Density

Molecular Modeling of Dimetal Systems. Part 2. Low-Order Dimolybdenum

[Re(η⁵-C₅H₅)(CO)₃]⁺ Family of 17-Electron Compounds: Monomer/Dimer Equilibria and Other Reactions

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Examination of n-beam interaction: X-ray experiment and simulation for KMnF3

Cited by 6 publications

References 8 publications

Correction of X-ray Intensities for Multiple Diffraction: Effects on Atomic Parameters and Charge Density

Correction of X-ray Intensities for Multiple Diffraction: Effects on Atomic Parameters and Charge Density

Molecular Modeling of Dimetal Systems. Part 2. Low-Order Dimolybdenum

[Re(η5-C5H5)(CO)3]+ Family of 17-Electron Compounds: Monomer/Dimer Equilibria and Other Reactions

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Product

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Examination of n-beam interaction: X-ray experiment and simulation for KMnF₃

[Re(η⁵-C₅H₅)(CO)₃]⁺ Family of 17-Electron Compounds: Monomer/Dimer Equilibria and Other Reactions