Oxidizing Elemental Platinum with Oleum under Harsh Conditions: The Unique Tris(disulfato)platinate(IV) [Pt(S2O7)3]2− Anion

For the first time, direct oxidation of elemental platinum by a mineral acid to its tetravalent state was observed in course of the reaction of platinum with oleum (65 % SO₃) in the presence of barium carbonate. The reaction has been carried out in torch‐sealed glass ampoules at 160 °C and gave yellow single crystals of Ba[Pt(S₂O₇)₃](H₂SO₄)_0.5(H₂S₂O₇)_0.5 (triclinic, P$\bar 1$ , Z=2, a=992.05(2), b=1069.07(3), c=1114.22(3) pm, α=69.49(7), β=72.96(2), γ=72.93(1)°, V=1033.95(5) ų). The structure of Ba[Pt(S₂O₇)₃](H₂SO₄)_0.5(H₂S₂O₇)_0.5 exhibits the unique tris‐(disulfato)‐platinate anion [Pt(S₂O₇)₃]^2? with three chelating disulfate groups coordinated to the platinum atom. Charge balance is achieved by the Ba²⁺ ions, which are coordinated by (S₂O₇)^2? groups from the platinate complex and by disordered sulfuric acids and disulfuric acid molecules. Thermal decomposition of the bulk material revealed elemental platinum and barium sulfate as decomposition residual.     

Pronounced in-plane anisotropy of phonon anomalies in YBa(2)Cu(3)O(6.6)

The dispersion of the Cu-O bond-stretching and bond-bending vibrations in YBa(2)Cu(3)O(6.6) has been studied by high resolution inelastic neutron scattering. While the behavior of the bond-bending vibrations can be well accounted for by a simple potential model, the bond-stretching vibrations show a highly anomalous behavior. The displacement pattern of the most anomalous phonons is in principle consistent with dynamic charge stripe formation. However, charge stripes would have to extend along the a axis and not the b axis as inferred from the magnetic fluctuations by Mook et al. [Nature (London) 404, 729 (2000)].     

Plasma-liquid technologies for treatment of archaelogical artifacts

Plasma-liquid technologies at atmospheric pressure provide a wide range of possibilities for applications. One of them, the treatment of archaeological artifacts, is presented in this paper. The effects of discharges between a metal electrode and a solution surface and/or an interaction of hollow cathode plasma jet, plasma pencil, with liquid on the corroded surface of bronze and glass artifacts were studied. It was compared with standard low pressure plasma techniques and with the effects of electrolysis. Original and treated objects were characterized by means of scanning electron microscope (SEM) with energy dispersive analyser used for the spot elemental analyses.     

Laser-induced multiphoton dissociation ofn-butyl ether

The pulsed CO₂-laser-induced multiphoton dissociation of n-butyl vinyl ether is studied. Comprehensive measurements have been performed for 9.6.μm and 10.6 μm irradiation. The corresponding dissociation product distributions show distinct differences for the two irradiation wavelengths, the most important finding being that acetylene is only produced at 9.6 μm.     

Representations of integers as sums of powers with increasing exponents

Let(n) be the least integer such thatn may be represented in the formn=x ₁ ² +x ₂ ³ +...+x _(n) ⁽ⁿ⁾⁺¹ wherex ₁,x ₂, ...,x _(n) are natural numbers. We computed(n) forn 250 000 and found that(n) 5 for all thesen exceptn=56, 160 for which(n)=6. Also(n) 4 for 41542<n<=250 000.     

Frontier orbital controlled cycloaddition of 2-azapentalenes

It is shown that cycloadditions of 1,3-bis (dimethylamino) pentalenes and their 2-aza-analogues with activated alkines are frontier orbital controlled whereas protonation is charge controlled.