Metal Complex Formation in Melts of Acetamide-Ammonium Nitrate-Water Mixtures, Part I. Cobalt(II) Chloride Complexes

Abstract

has been investigated. Absorption spectra of cobalt(II) chloride containing variable amounts of ammonium chloride were recorded at 45 to 60 • C. In the absence of chloride, the solutions show spectra typical for octahedral co-ordination of cobalt(II). Addition of chloride caused a shift of the absorption maximum toward lower energies and an increase of the molar absorption coefficient with increasing chloride concentration. The position of the absorption maximum and the intensity of the absorption indicate tetrahedral or severely distorted octahedral co-ordination. The stability constants for [Co(NO 3 ) 4 ] 2− , [Co(NO 3 ) 2 Cl 2 ] 2− and [CoCl 4 ] 2− complex formation in NH 4 NO 3 ·2.61CH 3 CONH 2 are reported.

Thermochromism, stability and thermodynamics of cobalt(ii) complexes in newly synthesized nitrate based ionic liquid and its photostability

“…In addition, it can be seen that 75 the position of the absorption maximum in the anhydrous system at 544 nm corresponds to the position of the absorption maxima ascribed to dodecahedral [Co(NO 3 ) 4 ] 2− complex species obtained in the anhydrous KNO 3 -LiNO 3 eutectic melt (λ max = 550 nm) 23 and eutectic mixture 0.723CH 3 CONH 2 -0.277NH 4 NO 3 (λ max = 80 538 nm). 24 In the system of [HO(CH 2 ) 2 mim]NO 3 ·3H 2 O an absorption maximum is shifted toward lower wavelengths (approximately at 515 nm) which corresponds to the position of the absorption maximum of octahedral cobalt(II) complexes obtained in the aqueous melt of Ca(NO 3 ) 2 ·4H 2 O (λ max = 512 85 nm) 25 and diluted aqueous solutions (λ max = 513 nm). 26 Addition of chloride ions to cobalt(II) nitrate solution caused a replacement of nitrate ions with chloride and formation of new absorbing species: 5 This change is followed by the change of colour from pale pink to dark blue (Fig.…”

Spectrophotometric Study of Cobalt (II) Chlorocomplexes in Methanol in the Visible Domain

“…Some authors have identified only one low intensity complex in aqueous solutions [26,27]. These studies have been extended in molten inorganic salts as well [28][29][30][31][32].…”

Specific Conductivities and Viscosities of 0.1LiNO3 + 0.9[xCH3CONH2 + (1 – x)CO(NH2)2] as Functions of Mole Fraction, x, and Temperature

“…Molten acetamide is highly polar solvent and exhibits “water-like” properties and many reports appeared since its exploration as a nonaqueous solvent . A variety of physicochemical properties of molten (acetamide + salt) and (urea + salt) mixtures have already been reported, − ,− ,− and studies of solute–solvent coupling in these media have also emerged recently. − …”