Calcium Halides Research Articles

Infrared spectra of carbon monoxide adsorbed on evaporated films of calcium halides

Infrared spectra of CO adsorbed at 77 K on evaporated films of CaF2, CaCl2, CaBr2 and CaI2 have been investigated. The system CO/CaCl2 has been studied in the far-infrared region.Two absorption bands have been found in each system. With CaF2, the main band at 2156 cm–1 has been assigned to molecules adsorbed on cations in the (111) face of the adsorbent. Heats of adsorption and spectral shifts have been calculated for this site. Fairly good agreement with experimental values has been found. These results and the reversible behaviour on desorption indicated that the adsorption is physical.In the other three systems, the frequencies of the main band depended strongly on coverage and varied from 2185–2190 cm–1 to ca. 2170 cm–1 with the amounts adsorbed. The desorption was reversible, but needed a much higher temperature (ca. 190 K). No additional evidence for charge transfer or complex formation has been found and therefore physical, although relatively strong, adsorption has been assumed.Assignments for the second band in each case have been suggested.

Sugar complexes with calcium ion: Infrared spectra of crystalline d-glucuronic acid and its calcium complexes

The Fourier-transform infrared spectra of d-glucuronic acid and three of its Ca 2+ complexes have been recorded. These complexes are of the type Ca( d-glucuronate)X · 3H 2O and Ca( d-glucuronate) 2 · 4H 2O, where X = Cl − or Br −. The structurally identified Ca( d-glucuronate)Br · 3H 2O shows that the octacoordination of each Ca 2+ ion is completed by three d-glucuronate residues and two water molecules. The d-glucuronate anion binds calcium cations through three chelation sites: one that involves a carboxyl-oxygen atom combined with O-5; one that includes the second carboxyl-oxygen atom acting in concert with O-4; and one involving the O-1–O-2 pair of hydroxyl groups. Spectroscopic evidence shows that the calcium halide complexes of d-glucuronic acid are structurally related in terms of 8-coordination and the common coordination-sites involved, whereas Ca( d-glucuronate) 2 · 4H 2O shows 8-coordination but in different structural arrangements. The strong, intermolecular hydrogen-bonding network of the free sugar is preserved upon metalation, whereas the intramolecular hydrogen-bonding system breaks down upon acid ionization. It is also evident that the d-glucuronate crystallizes as the α anomer in this series of metal complexes.

A Convenient Method for the Preparation of Highly Pure t-Alkyl Bromides and Iodides

Abstract Highly pure (99–100%) t-butyl and t-pentyl bromides and iodides, and 3-bromo-3-ethylpentane were readily prepared in 83–95% yields by the reactions of the corresponding alcohols with hydrobromic or hydroiodic acid, using lithium or calcium halide. The metal halides remarkably increased the yield and the purity of the products.

Sb3+ and Mn2+ Activated Calcium Halophosphate Phosphors from Flux‐Grown Apatites

The crystallization of calcium chloro‐ and chloro‐fluoroapatites from calcium halide fluxes was studied as a function of composition and heating schedules. Activation of was investigated by varying phosphor stoichiometry and firing methods. The results indicate that flux‐grown apatites are slightly deficient in and that for a particle size of predominantly 50–100μ, 72‐hr firing at 1150°C causes only limited incorporation of Sb3+ , Cd2+, and additional . The incorporation of Mn2+ is more extensive and may be nearly uniform. The rate of migration of Mn and Sb toward the interior of the crystals increases with increasing [as ] added prior to activation; however, maximum emission occurs at a calculated over‐all metal/phosphorus ratio of exactly 5/3. High output of heterogeneously emitting crystals suggests that quantum efficiency is independent of activator concentration.

Formation of Complex Compounds between Urea and Alkaline Earth Halides. XI. The Systems CaX2CO(NH2)2H2O. (Conductivity and viscosity)

AbstractAfter studying the systems: Barium halide‐urea‐water and strontium halide‐urea‐water (loc. cit.), it was of interest to extend the investigations to calcium halides, to discover the analogous and other complex compounds, if any, more in solution.The measurements of conductivity and viscosity of the mixed solutions of calcium chloride‐urea, calcium bromide‐urea and calcium iodide‐urea, indicated the existence of five definite complexes in solution, the formulae of the compounds are: (1) CaX2 · CO(NH2)2, (2) CaX2 · 2 CO(NH2)2, (3) CaX2 · 3 CO(NH2)2, (4) CaX2 · 4 CO(NH2)2 and (5) CaX2 · 6 CO(NH2)2.

Band spectrum of aluminium bromide (AlBr)

Our knowledge of the band spectra of the diatomic halides of Group III of the Periodic Table is confined at present to boron chloride (BCl) and aluminium chloride (AlCl). Whilst the data concerning BCl are fragmentary and uncertain, the vibrational structure of the AlCl molecule has recently been investigated by Mahanti and by Bhaduri and Fowler. An examination of known halide spectra shows that for a given positive radical the spectra all lie in the same wave-length region and are usually of the sequence type. With increasing halogen mass the system origin moves towards longer wave-lengths and the corresponding vibration frequencies progressively decrease. To illustrate these points, the relevant data for the calcium halides is shown in Table I, calcium being chosen as being the nearest element to aluminium whose halide spectra have been investigated.