Study of the Structure and Reactions of Bis(μ-Oxalato)tetramminediplatinum(II) in Aqueous Chloride Solutions

A comparison study of the bis(-oxalato)tetramminediplatinum(II) dimer [Pt₂(NH₃)₄(-C₂O₄)₂] and the oxalatodiammineplatinum(II) chelate [Pt(NH₃)₂C₂O₄] is performed. The kinetics and mechanism of substitution of C₂O^2– ₄ for Cl^– in aqueous chloride solutions are studied by photoelectronic spectroscopy, gravimetry, and chemical phase analysis within the 1.0–6.7 pH range at 75°C. The rate constants of substitution and the equilibrium constants for a two-step protonation for the dimeric and chelate complexes are calculated. Their solubility in 1 M KCl at 75°C; is determined. The unit cell parameters for [Pt₂(NH₃)₄(-C₂O₄)₂] are determined: a = 3.858 Å, b = 10.704 Å, c = 6.795 Å, = 94.35°. The IR spectra of [Pt(NH₃)₂C₂O₄], [Pt₂(NH₃)₄(-C₂O₄)₂], and their deuterated analogs are studied.     

Structural properties and state of the surface layer of zirconium dioxide promoted by manganese cations

The effect of Mn cations on the structural properties of zirconium dioxide (phase composition and crystallite size) was studied. The cations were introduced by coprecipitation of hydroxide precursors followed by thermal processing at temperatures of 350 to 650°C. It was found by X-ray photoelectron spectroscopy that Mn ⁿ⁺ cations (4 ≥ n ≥ 2, n = 3 being the dominant state) were localized on the surface of MnO _x -ZrO₂ samples calcinated at 350 and 600°C.     

Structural properties and state of the surface layer of zirconium dioxide modified by tungstate anions

A tetragonal metastable phase of zirconium dioxide formed after the addition of tungstate anions (>13 mol %) to the hydroxide precursor by different methods with heating (600–700°C), as revealed by X-ray diffraction analysis and X-ray photoelectron and IR spectroscopy. The W⁶⁺ and W⁵⁺ cations formed a solid solution with ZrO₂. On the surface of the solid solution, the tungsten cations formed tungstate clusters (?WO _x ?)n. The formation of the WO₃ phase was observed at concentrations of tungstate anions higher than 17.6 mol % or at temperatures of 850–870°C.