scholarly journals Kinetic Studies of Reduction of Tris-(1,1,1,5,5,5-hexafluoroacetylacetonato) ruthenium(III) in Methanol, Ethanol and Propanol

2011 ◽  
Vol 8 (3) ◽  
pp. 1006-1013 ◽  
Author(s):  
Ezekiel Dixon Dikio
Keyword(s):  
Magnetic Susceptibility ◽  
Oxidation State ◽  
Kinetic Studies ◽  
Molar Absorptivity ◽  
Kinetic Investigation ◽  
Absorption Bands ◽  
Spin Configuration ◽  
Spectroscopic Measurements ◽  
Bohr Magneton ◽  
A Value

The complex tris-(1,1,1,5,5,5-hexafluoroacetylacetonato-) ruthenium(III), hereafter referred to as Ru(hfacac)3, has been synthesized. Ultraviolet and visible spectroscopic measurements of the complex in ethanol revealed three prominent absorption bands at 287, 374 and 525 nm with molar absorptivity coefficients of 4.113, 3.885 and 3.59 respectively. Magnetic susceptibility measurements between 78 and 296 K revealed the complex to assume a low spin configuration of e0t2g5and an oxidation state of +3 as inferred from a value of 1.92 Bohr magneton. Kinetic investigation of the reduction of the complex in methanol, ethanol and propanol indicate the reduction to proceed in the order methanol > ethanol > propanol. The energies of activation of the reduction in methanol and ethanol were found to be 85.4 and 108 kJ/mol respectively.

Quantitative Infrared Absorption Measurements on Tri-n-Butyl Phosphate

1980 ◽  
Vol 34 (4) ◽  
pp. 415-417 ◽  
Author(s):  
Vincent P. Tomaselli ◽  
Hassan Zarrabi ◽  
K. D. Möller
Keyword(s):  
Infrared Absorption ◽  
Molar Absorptivity ◽  
Measured Data ◽  
Pure Liquid ◽  
Absorption Bands ◽  
A Value ◽  
Self Association ◽  
Solvent Molecules ◽  
Infrared Absorption Bands ◽  
Absorption Measurements

The molar absorptivity, ε(ν̄) of three intense infrared absorption bands in tri- n-butyl phosphate has been measured as a function of concentration. For all three bands, ε(ν̄) is independent of concentration for dilute solutions, then decreases uniformly with increasing concentration, and finally becomes independent of concentration again as one approaches the pure liquid. A saturation effect is found at about 1.0 M for all cases. Deviations from Beer's law behavior are observed at concentrations which depend upon the absorption band and/or the choice of nonpolar solvent. Self-association of the solute molecules is considered to be the cause of the decrease in ε(ν̄) with increasing concentration. From the measured data, it is possible to estimate the number of solvent molecules required to prevent this self-association. For CCl4, we find this value to be 25 molecules of solvent per solute molecule, a value in agreement with elementary geometric consideration.

The AMPIX electrochemical cell: a versatile apparatus forin situX-ray scattering and spectroscopic measurements

2012 ◽  
Vol 45 (6) ◽  
pp. 1261-1269 ◽  
Author(s):  
Olaf J. Borkiewicz ◽  
Badri Shyam ◽  
Kamila M. Wiaderek ◽  
Charles Kurtz ◽  
Peter J. Chupas ◽  
...  
Keyword(s):  
Electrochemical Cell ◽  
Function Analysis ◽  
Kinetic Studies ◽  
Spectroscopic Measurements ◽  
Battery Materials ◽  
X Ray ◽  
Complex Processes ◽  
Electrochemical Cycling ◽  
Ray Scattering

This article presents a versatile easy-to-use electrochemical cell suitable forin operando,in situmeasurements of battery materials during electrochemical cycling using a variety of X-ray techniques. Argonne's multi-purposein situX-ray (AMPIX) cell provides reliable electrochemical cycling over extended periods owing to the uniform stack pressure applied by rigid X-ray windows and the formation of a high-fidelity hermetic seal. The suitability of the AMPIX cell for a broad range of synchrotron-based X-ray scattering and spectroscopic measurements has been demonstrated with studies at eight Advanced Photon Source beamlines to date. Compatible techniques include pair distribution function analysis, high-resolution powder diffraction, small-angle scattering and X-ray absorption spectroscopy. These techniques probe a broad range of electronic, structural and morphological features relevant to battery materials. The AMPIX cell enables experiments providing greater insight into the complex processes that occur in operating batteries by allowing the electrochemical reactions to be probed at fine reaction intervals with greater consistency (within the charge–discharge cycle and between different methodologies) with potential for new time-dependent kinetic studies or studies of transient species. Representative X-ray and electrochemical data to demonstrate the functionality of the AMPIX cell are presented.

Vibration-rotation bands and rotational constants of dideuteroacetylene

1955 ◽  
Vol 232 (1190) ◽  
pp. 291-309 ◽  
Keyword(s):  
Resolving Power ◽  
Vibrational States ◽  
Absorption Bands ◽  
Rotational Constants ◽  
Vibrational Assignments ◽  
Vibrational Anharmonicity ◽  
A Value ◽  
Vibrational Levels ◽  
Vibration Rotation ◽  
Very High

Nine vibrational absorption bands of dideutero-acetylene have been examined with very high resolving power. The rotational constants have been determined for the vibrational levels concerned, and the coefficients α i have been determined with more convincing accuracy than previously. In some of the bands the Q branches have been resolved, so that the l -doubling coefficients q i could be derived, and details could be established about the doublet components in some II levels. The results emphasize the need of high resolution if the vibrational assignments are to be unambiguous, and if reliable values of the rotational constants are to be derived. A value of B e has been obtained, and the vibrational anharmonicity coefficients have been considered briefly. Estimates of the centrifugal stretching constants D i in different vibrational states have been made, and one anomalous case has been found.

Spectroscopic and electrical studies of all- trans β-carotene crystals

1967 ◽  
Vol 301 (1465) ◽  
pp. 173-193 ◽  
Keyword(s):  
Electronic Absorption Spectra ◽  
Dark Conductivity ◽  
Electrical Measurements ◽  
Absorption Bands ◽  
A Value ◽  
Polarization Behaviour ◽  
Current Characteristics ◽  
Β Carotene ◽  
Weak Peak

Single crystals of all- trans β -carotene have been grown and spectroscopic, optical and electrical properties measured. Electronic absorption spectra have been measured at liquid nitrogen and room temperature, and the polarization of the absorption bands in the mono-clinic form determined. The polarization behaviour is briefly discussed. The electrical measurements include a determination of the dark conductivity, giving a value for the electrical activation energy of 1·45 eV. Some crystals were observed to give unusual voltage current characteristics and to give rise to current pulses at a steady applied voltage. Photoconductivity measurements show a weak peak at 25000 cm -1 in the region where maximum light absorption occurs, and a much stronger peak at 13300 cm -1 . The various processes which could be responsible for this and for the origin of the latter peak are discussed.

scholarly journals Quinolone Antibacterials: Commentary and Considerations Regarding UV Spectra and Chemical Structure

2015 ◽  
Vol 61 (4) ◽  
pp. 328-336 ◽  
Author(s):  
Rusu Aura ◽  
Imre Silvia ◽  
Mircia Eleonora ◽  
Hancu Gabriel
Keyword(s):  
Analytical Methods ◽  
Chemical Structure ◽  
Kinetic Studies ◽  
General Characteristic ◽  
Protonated Form ◽  
Uv Spectra ◽  
Spectrophotometric Analysis ◽  
Model Compounds ◽  
Absorption Bands ◽  
Quinolone Derivatives

AbstractObjective: Antibacterial quinolones represent an important class of pharmaceutical compounds that are widely used in therapy. Analytical methods that rely on their property to absorb light in the UV range are commonly used for their analysis. In the current study we present an interpretation of the relationship between chemical structure – UV spectra based on the comparative examination of UV spectral behavior of the eighteen quinolone derivatives and four model compounds.Methods: Eighteen quinolone derivatives and four model compounds were selected and their UV spectra were recorded in different solvents (methanol, 0.1M HCl, 0.1M NaOH).Results: The studied compounds show three absorption maximum values located around 210-230 nm, 270-300 nm and 315-330 nm values. A general characteristic was observed as the absorption bands exhibited both hypsochrome and bathochrome shifts, by comparison in different solvents. Most commonly we observed a slight hypsochrome shift at acidic pH (protonated form prevails) and basic pH (anionic form prevails). The structural differences are reflected in changes of UV spectra only when there are auxochrom substituents or different basic substituents are present in the quinolones structure.Conclusions: The correlations between the chemical structure of quinolone derivatives and their UV spectra using model compounds were established. This study provides useful information that can be used successfully in various UV spectrophotometric analysis methods or in more complex analytical methods using UV detection, and also in pharmacodynamic and kinetic studies.

Thermodynamics of metal-ligand bond formation. IV. Base adducts of Bis(ethylxanthato)nickel(II) and Bis(dialkyldithiophosphato)nickel(II)

1971 ◽  
Vol 24 (12) ◽  
pp. 2509 ◽  
Author(s):  
DR Dakternieks ◽  
DP Graddon
Keyword(s):  
Magnetic Susceptibility ◽  
High Spin ◽  
Thermodynamic Data ◽  
Benzene Solution ◽  
Bond Formation ◽  
Spin Configuration ◽  
Thermometric Titration ◽  
Metal Ligand ◽  
Ligand Bond

The reactions of pyridine with bis(ethylxanthato)nickel(~~) and bis(dipropy1- dithiophosphato)nickel(~~) and of pyridine, 4-methylpyridine, bipyridyl, and 2,9-dimethyl-l,l0-phenanthroline with bis(diethyldithiophosphato)nickel(~~) have been studied by thermometric titration in benzene solution a t 30�C. The xanthate adds two molecules of pyridine simultaneously, AHolz = -75 kJ mol-1, ASOlz = -186 J K-1 mol-1. With the dithiophosphates, two molecules of base are added in distinct steps; the enthalpy of addition of bipyridyl is similar to that of two molecules of pyridine, but the enthalpy of addition of 2,9-dimethyl-l,l0- phenanthroline is much smaller. The thermodynamic data obtained for these reactions are as follows (AH" in k J mol-1, AS0 in J K-1 mol-1) : dipropyldithiophosphate with py AHol -71, AS01 -211, AHoz 4-2, AS0$ +34 diethyldithiophosphate PY -73 -218 +4 + 40 diethyldithiophosphate 4-mepy - 83 -248 + 7 + 59 diethyldithiophosphate bipy -76 diethyldithiophosphate Mesphen -47 Determination of the magnetic susceptibility in benzene solution containing varying pyridine concentrations has shown that base adducts of the dithiophosphates of both the types NiLzB and NiLzBz have the metal atom in the high-spin configuration.

Rates of elementary processes in the chain reaction between hydrogen and oxygen II. Kinetics of the reaction of hydrogen atoms with molecular oxygen

1963 ◽  
Vol 275 (1363) ◽  
pp. 559-574 ◽  
Keyword(s):  
Molecular Oxygen ◽  
Kinetic Studies ◽  
Negative Temperature ◽  
Product Analysis ◽  
Hydrogen Atoms ◽  
The Third ◽  
Rate Determining Step ◽  
A Value ◽  
Explosion Limit ◽  
Kinetics Of

The addition of molecular oxygen was found to increase the rate of rem oval of hydrogen atoms in a flow system at and below room temperature. Kinetic studies of this process using argon carrier showed that the rate-determining step is the third-order reaction H + O2 + Ar = HO 2 + Ar. (2) Atomic oxygen in small concentrations is produced in the system. Product analysis and measurements of oxygen atom concentrations indicated that the principal reactions removing HO 2 under these conditions are H+HO 2 = H 2 +O 2 , (12a) H+HO 2 = OH+OH, (12b) H+HO 2 = H 2 O+O 2 , (12c) A value for k 2 of 2.2 x 10 -32 cm 6 molecule -2 s -1 was determined at 293 °K. Reaction (2) was found to have a small negative temperature coefficient. These data and values of k 2 from explosion limit studies can be represented by the expression k 2 = 1.3 x 10 -33 exp (+ 1600 + 700/ RT ) cm 6 molecule -2 s -1 in the range 250 to 800 °K. The third-body efficiencies in reaction (2) at 293 °K of He and H 2 O relative to Ar are similar to those obtained from data on the second explosion limit at higher temperatures.

scholarly journals Effect of Bi Substitution on Structural and AC Magnetic Susceptibility Properties of Nd1−xBixMnO3

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 521 ◽  
Author(s):  
Nurul Atiqah Azhar ◽  
Intan Solehah Ismail ◽  
Nur Baizura Mohamed ◽  
Azhan Hashim ◽  
Zakiah Mohamed
Keyword(s):  
Magnetic Susceptibility ◽  
Single Phase ◽  
Lattice Parameter ◽  
Ac Magnetic Susceptibility ◽  
X Ray Diffraction ◽  
Absorption Bands ◽  
Pbnm Space Group ◽  
Bi Doping ◽  
Stretching Vibration ◽  
Crystal Structural

This study synthesizes the neodymium-based manganites with Bi doping, Nd1−xBixMnO3 (x = 0, 0.25 and 0.50) using the solid-state reaction route. The crystal structural, morphological and magnetic properties were determined using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and AC magnetic susceptibility. The Rietveld refinement confirmed that the compounds were in the single-phase orthorhombic structure of the NdMnO3 with Pbnm space group and lattice parameter b increased with doping from 5.5571 (x = 0) to 5.6787 (x = 0.5). FTIR spectra showed that absorption bands were located within the range of 550–600 cm−1, which corresponded to the Mn–O stretching vibration. FESEM exhibited homogenous compound. The AC magnetic susceptibility measurement studies showed a strong antiferromagnetic (AFM) to paramagnetic (PM) transition existed at 76 K, 77 K and 67 K for samples (x = 0, 0.25 and 0.50), respectively.

Structural interpretation of polarized absorption spectra of the Al-Fe-Mn-Cr epidotes

1967 ◽  
Vol 36 (278) ◽  
pp. 204-226 ◽  
Author(s):  
R. G. Burns ◽  
R. G. J. Strens
Keyword(s):  
Magnetic Susceptibility ◽  
Absorption Spectra ◽  
Orthorhombic Symmetry ◽  
Absorption Bands ◽  
Site Preferences ◽  
Coordination Sites ◽  
Jahn Teller ◽  
Splitting Parameter ◽  
Spin Electronic ◽  
Universal Stage

SummaryMeasurements have been made of the magnetic susceptibility and of the polarized absorption spectra of epidotes of the Al-Fe, Al-Fe-Mn, and Al-Cr series. Magnetic susceptibility measurements at room temperature by the Guoy method indicate that Fe3+, Mn3+, and Cr3+ are in ‘high-spin’ electronic states in the epidote structure, and the electronic transitions observed in the absorption spectra have been assigned on this basis. The polarized spectra, measured over the range 4000 to 22 000 Å by a polarizing microscope using a universal stage technique, showed each epidote group to be distinctly pleochroic. This pleochroism correlates with the presence of ions in distorted coordination sites.Extinction coefficients of Fe3+ in epidote are higher than those for other Fe (III) compounds, indicating that Fe3+ ions occupy the non-centrosymmetric (Al, Fe) site. The low value (13200 cm−1 at 0·155 Fe3+ and 12700 cm−1 at 0·915 Fe3+) of the crystal-field splitting parameter, Δ, implies that the site is easily expanded to accommodate ions larger than Al3+ There is also evidence that increasing Fe3+ content causes distortion of the (Al,Fe)O6 octahedron, suggesting a possible mechanism for the zoisite ⇌ clinozoisite transition.The spectra of Al-Mu-Fe epidotes have been interpreted in terms of intense contributions from Mn3+ ions in the non-centrosymmetric (Al, Fe) site, and weak contributions from Mn3+ ions in the centrosymmetrie AlOH site. Values of Δ vary from 13730 cm−1 (0·082 Mn3+) to 13400 cm−1 (0·747 Mn3+). Both (Al, Fc) and AlOH sites have strong tetragonal distortions (c/a ~ 0·95), leading to the observed large Jahn-Teller splitting of 12000 cm−1.The Al-Cr epidote spectra show weak absorption bands, attributed to Cr3+ ions in a centrosymmetric site of approximately orthorhombic symmetry (i.e. the AlO site). The value of Δ is about 16300 cm−1.Review of all available data on the distribution of Fe3+, Mn3+, and Cr3+ between the sites gives the following site preferences: Fe3+, Al > AlO > AlOH; Mn3+, Al ≥ AlOH ≫ AlO ; Cr3+, AlO ≫ Al, AlOH.

Transition Metal Complexes of Ambidinourea and Related Ligands.

1969 ◽  
Vol 24 (12) ◽  
pp. 1514-1517 ◽  
Author(s):  
A. Syamal
Keyword(s):  
Magnetic Susceptibility ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Electronic Spectra ◽  
Strong Field ◽  
Absorption Bands ◽  
Effect Of Solvents ◽  
Infra Red ◽  
Solid Complexes

Copper (II), nickel (II), and palladium (II) complexes of amidinourea are reinvestigated in order to verify their structure. Electronic spectra and magnetic susceptibility measurements have been obtained on the solid complexes. Electronic spectral results indicate the donor strength of amidinourea is comparable to strong field ligands like biuret, biguanide, and I-amidino-O-alkylurea. Infra-red spectral results suggest that the carbonyl group of amidinourea is not involved in coordination and the donor atoms in amidinourea are amide nitrogens. The effect of solvents on the absorption bands is also discussed. The solution absorption spectra of bis (amidinourea) copper (II) chloride in different solvents indicate the following order of decreasing tetragonality:DMSO > methanol > ethyleneglycol > water.

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