Substitution of coordinated chlorides in cis-α and cis-β dichloro (triethylene tetramine) cobalt(III) chloride [Co(trien)Cl2]Cl by thiocyanate in aqueous medium

Substitution of coordinated chlorides in cis-α, and cis-β dichloro (triethylene tetramine) cobalt(III) chloride by thiocyanate was studied in aqueous medium in the pH range 3.8 to 4.0 at 25–26° C. Substitution, as in aquation, took place in two steps corresponding to the two chlorides, one step being faster than the other. Mechanisms have been discussed in the paper.     

Halogen nuclear magnetic resonance shifts

The nuclear magnetic resonance shifts (chemical shifts) of Cl³⁵ in aqueous solutions of alkali chlorides were determined using a High Resolution NMR Spectrometer. These small shifts probably represent the effect of the neighbouring atom even in the highly ionic state. A similarity of these results to the quadrupole coupling constants of the halogen atom in these molecules is pointed out.     

The ionic character of singly bonded molecules

The overlap factors for bond electrons in various diatomic halides are calculated making use of a simple relation where the overlap factor is an inverse exponential function of the difference between the two atomic radii of the molecule concerned. These overlap factors together with the hybridization values of 15 percent for Cl, and 10 percent for Br and I are used to calculate the ionic characters for various diatomic molecules from the values of the nuclear quadrupole coupling constants obtained by earlier workers. These ionic characters are then plotted against electronegativity differences and the points are found to be fairly well represented by a smooth curve. It is shown that this curve can in general be used for the determination of the ionic characters in the halogen containing single bonds of certain polyatomic molecules. The quadrupole coupling constants are calculated from the ionic characters obtained from the curve and are compared with those observed. The effects of the distortion of the closed shells and of the neighbouring ions oneQq are discussed.     

Electron paramagnetic resonance of CU2+ ion in CsCl single crystals

Electron paramagnetic resonance spectrum of the Cu²⁺ ion in CsCl is studied at different temperatures. The local symmetry at the Cu²⁺ site is found to be tetragonal. A model of substitutional Cu²⁺ ion associated with a first neighbour cation vacancy is proposed to explain the observed spectrum.     

Electron spin resonance of Mn2+ in NaCl single crystal and lattice defects

The electron spin resonance spectra of Mn²⁺ in NaCl single crystals are investigated in detail. Seven different spectra (I, II, III₁, III₂, IV, V and VI) are observed. The spectra I–IV are the same as those observed by earlier workers, while the spectra V and VI are observed here for the first time. The local symmetry at the paramagnetic ion is orthorhombic for the spectra IV and V and tetragonal for the spectrum VI about the crystallographic [001] direction. The properties of the spectrum IV are explained in terms of an associated pair Mn²⁺: O₂ ^2? with O₂ ^2? molecular ion at the nearest neighbour anion site in the [001] direction with its internuclear axis in the (001) plane. The spectrum V is assigned to the associated pair Mn²⁺: O₂ ^2? coupled with a nearby cation vacancy in the [001] direction and the spectrum VI to Mn²⁺ ion associated with OH^? ion at the anion site in the [001] direction with a probable second neighbour cation vacancy. All the observed spectra are analysed in terms of the parameters of the usual spin-Hamiltonian.     

Anharmonicity factors and potential energy constants of B2H6 and B2D6

The anharmonicity factors of B₂H₆ and B₂D₆ have been calculated using Dennison’s method. Using the calculated harmonic wave numbers, the valence force constants have been obtained by the Wilson’s F-G matrix method.     

Uranyl-alizarin red-s complex.a spectrophotometric study

From spectrochemical studies on the blue complex resulting from uranyl and alizarin-S, it has been shown that a compound in the stoichiometric ratio 1:1 of uranyl and reagent is formed. The compound is stable at pH 8.2. The peaks of absorption of the reagent at 520 mu; and of the uranyl compound at 570 mμ have been accounted for, applying kuhn's relationship.     

Mean amplitudes of vibration and coriolis coupling constants of some XY3Z type silicon compounds

A theoretical treatment of the generalised mean-square amplitudes of vibration of some silicon compounds of XY₃Z type molecules is presented. The numerical values evaluated for the parallel and perpendicular mean-square amplitudes for all the bonded and non-bonded atom pairs are tabulated. The L matrix elements and Coriolis coefficients have also been evaluated for these molecules.     

Intensity studies in Raman effect

The intensities of Raman lines due to CH, CH₂ and CH₃ groups in the case of some n-paraffin hydrocarbons have been obtained relative to the peak intensity of the 458 cm^?1 line of CCl₄ and compared. The integrated intensity as well as the standard intensity of the C=O frequency in some unconjugated and conjugated ketones, aldehydes and esters have been obtained and the influence of conjugation has been discussed. The intensity of the C=C frequency has also been obtained in the conjugated compounds and compared with the results obtained for the unconjugated compounds.