The magnetic circular dichroism spectrum of matrix-isolated oxygen

The magnetic circular dichroism spectrum of atmospheric oxygen condensed on a cold window has been measured in the region from 240–270 nm. Analysis of the spectrum shows that the transition observed is ³Σ_g^? → ³Δ_u. The corresponding absorption has previously been observed only in the gas phase using very long path lengths or high pressures.     

Synthesis and circular dichroism studies of some cobalt(III) complexes containing 2,2′ bipyridine, 1,10 phenanthroline,and some optically active amino acids

Two series of cobalt(III) complexes were synthesized and spectrally analyzed, [Co(2,2′-bipyridyl)₂(aa)]I₂ and [Co(1,10-phenanthroline)₂(aa)]I₂ (where the letters aa refer to an optically active, bidentate amino acid). The following amino acids were used: l-alanine, glycine, l-leucine, l-phenylalanine, and l-proline.This research is an analogue to the chemical systems studied by Mason et al.^1,2 They investigated complexes such as [Co(phen)₃]³⁺, [Co(dipy)₃]³⁺, [Co(phen)₂(dipy)]³⁺, [Co(dipy)₂(phen)]³⁺, [Co(phen)₂(ox)]²⁺, and [Co(dipy)₂(ox)]²⁺. The series of [Co(dipy)₂(na)]²⁺ and [Co(phen)₂(na)]²⁺ complexes, where the letters na refer to a non-optically active, bidentate ligand, have exhibited exciton-splitting. We used optically active amino acids to ascertain whether or not the exciton-splitting phenomenon would occur when a non-optically active ligand was substituted by an optically active amino acid. In addition, a series of optically active amino acids was selected with the intention of determining whether small differences among the amino acid ligands would affect the circular dichroism (CD) spectra of the different complexes and if the formation of these complex ions would be steroselective.     

The raman spectrum and structure of dicyclopentadienylberyllium

The Raman spectra of solid and liquid dicyclopentadienylberyllium are described. They suggest the presence of two π-bonded rings in the molecule, one pentahapto and one polyhapto coordinated to the Be atom.     

The polarized infrared spectrum of crystalline dimethyl oxalate

The polarized infrared spectra of oriented crystal films of dimethyl oxalate have been recorded at approximately 20 K. The symmetry species of the intramolecular modes have been determined on the basis of the polarization behavior of the observed bands and compared to the assignments made by previous workers by indirect methods. The Davydov components in some of the bands are observed and assigned to the infrared active factor group symmetry species A_u and B_u.     

The study of enantioselectivity in copper complexes with some 1,3-dicarbonyl ligands by circular dichroism spectroscopy

The circular dichroism spectra of copper(II) complexes with hydroxymethylene camphor, hydroxymethylene menthone, and trifluoroacetyl camphor as well as of mixed-ligand complexes with acetylacetone have been studied in different solvents at different temperatures. The changes observed in the spectra are attributed to a strong coordination of the solvent molecules in axial positions of square-planar complexes. It has been shown that the contributions of two ligands to the net spectrum of circular dichroism are additive and that the absorption spectra of the complexes do not depend on the optical configuration of the ligands. The conclusion has been drawn that no noticeable inter-ligand interactions exist in the complex and no enantioselective effects are exhibited.     

Temperature dependence of the Mössbauer spectrum and magnetic susceptibility [Fe(uridine)Cl2]∞: Novel magnetic ordering of transition metal complexes based on nucleoside ligands

The zero-field Mössbauer spectra and magnetic susceptibility of a polycrystalline sample of the polymeric material [Fe(uridine)Cl₂]_∞ have been measured in the temperature range 1.7-300 K. The compound exhibits two magnetic transitions. The isomer shift and quadrupole splitting indicate a distorted pseudo-octahedral FeCl₄O₂ chromophore resulting from condensation to a network structure via chloro and uridine ligand bridging.     

X-ray K-absorption spectrum of yttrium in some yttrium pyrochlores

The X-ray K-absorption edge of yttrium in some pyrochlores of the type YLnFeSbO₇ have been investigated using a 400 mm bent crystal spectrograph. The position of the principal absorption edge was found to have shifted towards the low energy side when Ln was changed from lanthanum through erbium. On the basis of the extended absorption fine structure estimates about the bond lengths have been made using the Lytle's and Levy's techniques.     

Circular dichroism of olefins—IV: A semiquantitative prediction of the intensity of the cotton effect of allyl alcohols and ethers

A semi quantitative prediction of the intensity of the Cotton effect of a few allyl alcohols and ethers in the steroid and diterpene series has been derived. It relies on a calculation of the weight of the various conformations and on the allylic bond polarization model.     

Absorption and magnetic circular dichroism spectra of CsBr:In+; moments analysis

Optical absorption and magnetic circular dichroism spectra of single crystals of CsBr:In⁺ have been measured at several temperatures in the range from 2.5 to 300 K. The moments of the corresponding lineshape spectra have been determined by numerical integration and, for the absorption spectra, also by band resolution. Good agreement between the results of the two methods is obtained, except at temperatures at which the bands overlap, where numerical integration cannot be expected to yield accurate results. The semiclassical approximation, which has hitherto been applied to the NaCl structure, has been modified for the CsCl structure and used to analyze the temperature dependence of the moments. This analysis yields the effective frequency ω_c of the lattice modes that couple with the excited electronic states. The electron-lattice coupling constants, which characterize the interaction of the electronic states of the impurity ion with lattice vibrations of A_1g, E_g and T_2g symmetry, have been evaluated for the |A> state and the temperature dependence of the orbital g factors $\text{g}$_A and $\text{g}$_B of the A and B bands has been determined.     

The crystal structure of Tl0.84V5Se8 and magnetic bulk properties

While the antiferromagnetic binary compound V₅Se₈ (Y. Kitaoka and H. Yasuoka, J. Phys. Soc. Jpn.48, 1460, 1980) of which the measured magnetic susceptibility above 27 K cannot be fitted to a Curie-Weiss law and a Curie-Weiss law with a term for the temperature-independent paramagnetism, the ternary compound Tl_0.84V₅Se₈ exhibits paramagnetism. The measured susceptibility fits the equation $\text{χ = χ}{}_0\text{+}\text{C}\text{(T ? θ)}$. In comparison to Tl_0.96V₅S₈ (W. Bensch, E. Amberger, and J. Abart, in press) with shorter VV distances than in Tl_0.84V₅Se₈, the magnetic moment attributed to V(3) in the selenide is markedly higher.     

Multinuclear magnetic resonance and related studies on some organotin(IV) complexes of dithiocarbazates

Synthesis, characterization and geometrical features of pentacoordinated dibutyltin(IV) dithiocarbazate complexes of the type n-Bu₂Sn L (where L = dianion of $\text{S}$-methyl-B-N (2-hydroxy-phenyl) methylene and methyl dithiocarbazate are described. These are obtained as viscous oils from the reactions of n-Bu₂SnO with equimolar proportions of the ligands in benzene. On the basis of UV, IR, NMR (¹H, ¹³C, ¹¹⁹Sn) spectra along with the mass spectral fragmentation pattern a trigonal bipyramidal geometry is proposed. The N atom probably occupies the axial site, while the remaining two donor atoms O and S and the dibutyl groups rest in an equatorial plane. These complexes are active against P.388 Lymphocyte leukaemia system.     

Absorption spectra,emission spectra,and magnetic susceptibility of chromium in sodium-β-alumina

Absorption spectra, emission spectra, and magnetic susceptibility from 4.2 to 300°K have been measured for β-alumina doped with $\text{2w}\text{o}$ chromium. Chromium-doped β-alumina sintered in air was found to contain only Cr(IV) even though Cr(III) was the oxidation state initially present. Heating air-sintered samples at 1200°C in $\text{10\% H}{}_2\text{90\% N}{}_2$ for 5 hr reduced the Cr(IV) to Cr(III). The absorption spectra for Cr(IV) and Cr(III) have been fitted to the Tanabe-Sugano diagram and Dq and B were calculated. Results are consistent with the assignment of both Cr(III) and Cr(IV) to octahedral coordination sites in β-alumina. A parallel study of chromium doped α-alumina also showed the existence of Cr(IV) and Cr(III) in that host lattice depending on the firing atmosphere.     

Spectral and magnetic studies of tin(IV) complexes with nickel(II) thiocarbohydrazones

Tin(IV) chloride derivatives of nickel(II) thiocarbohydrazones were obtained by reacting tin(IV) chloride with nickel(II) thiocarbohydrazones in chloroform medium. All the complexes are greenish coloured solids and appear to be non-electrolytes in DMF. Elemental analyses conform to the 1:1 stoichiometry. Magnetic, electronic and IR spectral information suggest that square planar nickel(II) thiocarbohydrazones have changed their configuration to octahedral as a result of reaction with tin (IV) chloride.     

Nuclear magnetic resonance study of aluminum chloride-n-Butylpyridinium chloride melts

High resolution proton and ¹³C-NMR measurements were used to follow the variation of the n-butylpyridinium (BP⁺) cation spectra in BP⁺Cl^?AlCl₃ molten mixtures. The mole fraction of AlCl₃ was varied between 0.45 and 0.60. It was found that chemical shifts and proton coupling constants are significantly affected by the BP⁺-Cl^? and BP⁺ -AlCl^?₄ associations. Analysis of the NMR results shows that in the melts the ionic association into ion pairs is essentially quantitative. Lithium-7 NMR of BPCl-AlCl₃-LiCl melt shows that when the mole-fraction of AlCl₃ is < 0.50 (basic melt) LiCl₂^? ion is formed, while in the acidic melts the Li⁺ ion probably interacts with two AlCl₄^? ions to form LiAl₂Cl^?₈ ion.     

The crystal structures and magnetic properties of Ba2LaRuO6 and Ca2LaRuO6

Profile analysis of high-resolution, powder neutron-diffraction data was used to refine the previously reported structures of the ordered, distorted perovskites Ba₂LaRuO₆ and Ca₂LaRuO₆. Low-temperature neutron diffraction experiments showed that, at 2K, the former is a Type IIIa antiferromagnet while the latter is Type I. Both compounds have an ordered magnetic moment of $\text{μ}{}_{\mathrm{<mtext>Ru</mtext>}}\text{? 1.95μ}{}_{\mathrm{<mtext>B</mtext>}}$ per Ru⁵⁺ ion. The Néel temperature of Ba₂LaRuO₆ was determined to be 29.5K, and the covalent mixing between the ruthenium and nearest-neighbor anions is described by A²_π = 8.2 ± 1% for Ba₂LaRuO₆ and 8.6 ± 1% for Ca₂LaRuO₆. The ionic radius of a Ru⁵⁺ ion is 0.56 Å. These data are consistently interpreted within the framework of a strongly correlated, half-filled π1 band. Extension of this interpretation to the magnetic data for the perovskites CaRuO₃ and SrRuO₃ leads to a fundamental theoretical prediction.     

The thermal decomposition,IR spectrum and crystal structure of ammonium manganese(II) tris(hydrogenselenite), NH4Mn(HSeO3)3

The compound NH₄Mn(HSeO₃)₃ has been prepared and its IR spectrum and thermal behaviour have been investigated. It crystallizes in the monoc     

Solvent effects on the electronic spectrum of the hexathiocyanatochromate (III) anions. A revised octahedral crystal field splitting parameter for the thiocyanate ion

An early report on the solvent dependence of the electronic spectra of complex ions considered the electrostatic effect of solvent molecules in the second coordination sphere, on the position of the absorption bands.¹ Solvent effects on the ligand field bands for solutions of K[Cr(NH₃₂(NCS)₄] have been discussed by Adamson² who emphasised a correlation between the solvent shifts in the spin-allowed bands and the shifts in the quartet-doublet bands. This work describes the effects of various solvents on the electronic absorption spectra of [Cr(CNS)₆]^3?.     

A spectrometric study of a 40 MHz inductively coupled plasma—VII: Continuum of a binary mixture in the visible region of the spectrum

The continuum of an argon-hydrogen plasma is determined both theoretically and experimentally using the determination of physical parameters of the ICP. Similarly to pure argon plasma, radiative recombination is the main process in the continuum formation, below 500 nm. The presence of hydrogen results in an increase of the excitation temperatures and the electron number density, linked with an enhancement of the continuum. On the other hand, easily ionizable elements such as Na and K have no influence on these parameters. The injection of hydrogen via water is the main cause of variation of the ICP physical parameters.