The Structure of Hyperalkaline Aqueous Solutions Containing High Concentrations of Gallium - a Solution X-ray Diffraction and Computational Study

Highly concentrated alkaline NaOH/Ga(OH)3 solutions with 1.18 M Ga(III)T 2.32 M and 2.4 M NaOHT 4.9 M (where the subscript T denotes total or analytical concentrations) have been prepared and investigated by solution X-ray diffraction and also by ab initio quantum chemical calculations. The data obtained are consistent with the presence of only one predominant Ga(III)-bearing species in these solutions, that is the tetrahedral hydroxo complex Ga(OH)4–. This finding is in stark contrast to that found for Al(III)-containing solutions of similar concentrations, in which, besides the monomeric complex, an oxo-bridged dimer was also found to form. From the solution X-ray diffraction measurements, the formation of the dimeric (OH)3Ga–O–Ga(OH)32– could not unambiguously be shown, however, from the comparison of experimental IR, Raman and 71Ga NMR spectra with calculated ones, its formation can be safely excluded. Moreover, higher mononuclear stepwise hydroxo complexes, like Ga(OH)63–, that have been claimed to exist by others in the literature, was not possible to experimentally detect in these solutions with any of the spectroscopic techniques used

Ambiguity of Electron Solvation Mechanisms in Polar liquids

The study of the criteria necessary for a solvation model to successfully interpret the most detailed recent experiments in pure methanol shows that the extent to which a solvent relaxation accompanied by a continuous spectral blueshift would contribute to the measured signal cannot be decided. We demonstrate that previously derived properties - like the time for the signal rise or fall, solvation time, branching ratio - from experimental solvation data are model dependent and cannot be used to choose between alternative solvation schemes

On the oximine complexes of transition metals, Part CXIII Protolytic equilibria in the solutions of some complexes of the type [Co(Diox.H_2 AB] with alpha-benzyldioxime and alpha-furyldioxime

11 complexes of the type [Co(Diox.H)_2 AB]^n (Diox.H)_2-alpha benzyldioxime (Diphenylglyoxime: Dif.H_2), alpha-furyldioxime furox.H_2), A, B, - CN^-, NO_2^-, HSO_3^-, SO_3^2-, H_2O, amine) were obtained by various substitution reactions, and characterized by middle IR and electronic spectral data. The protolytic equilibria: [Co(Diox.H)_2 AB]^n \leftrightarrows H^+ [Co(Diox.H)(Diox)AB]^n-1 + \leftrightarrows H^+ of these complexes in aqueous solutions were studied by potentiometric and spectrophotometric measurements (in Britton-Robinson buffer solutions). The complicated character of these processes (5 equilibria in a wide pH range) was discussed