Molecular structure of potassium [N,N′-bis(salicylideneamino)nitroguanidonate-N,N′,-O,O′]nickel(ii), the product of condensation of (salicylideneamino)nitroguanidine with salicylaldehyde on a Ni2+ ion template

The crystal structure of the product of the condensation of (salicylideneamino)nitroguanidine with salicylaldehyde on a Ni²⁺ ion template, K[Ni(C₁₅H₁₀N₅O₄)] · DMF, has been studied. It was established that a planar Ni complex, consisting of isolated [NiL]^– anions and solvated [K⁺ · DMF] cations, is formed. The negative charge of the anion is localized mainly on the O atoms of the nitro group. The nitroguanidine fragment of the ligand occurs in the tautomeric form, which was not reported previously.Deceased in 1995Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2273–2277, September, 1996.     

Synthesis and structure of tetraphenylantimony hydrogen phthalate

Tetraphenylantimony hydrogen phthalate, Ph4SbOC(O)C6H4000H-o, was prepared by the reaction of pentaphenylantimony with phthalic acid. According to the data of X-ray structural analysis, the resulting compound is a trigonal-bipyramidal complex of antimony with three phenyl groups in equatorial positions; the fourth phenyl group and the carboxyl fragment are in axial positions. The CSbO angle is 177.5(1)° the Sb-C(Ph)_eq and Sb-C(Ph)ax distances are 2.099(4)-2.177(4) A and 2.129(4) A, respectively. The H atom of the free carboxyl group and the carbonyl O atom of another carboxylate group form an intramolecular hydrogen bond.DeceasedTranslated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 2082–2085, August, 1996.     

New reactions of sulphur dichloride with olefines

The interaction between SCl₂ and adamantylideneadamantane produces epithiocompounds $\text{2}$ and $\text{3}$ or polychloroadamantylideneadamantanes $\text{4}$–$\text{7}$ depending upon conditions. The structure of $\text{3}$ was determined by X-ray analysis.     

Tantalum(v) oxoalkoxides. Synthesis and structure

Anodic oxidation of tantalum in isopropyl alcohol or prolonged reflux of an alcohol solution of Ta(OPrⁱ)₅ afford crystalline oxoisopropoxide Ta₂O(OPrⁱ)₈ · PrⁱOH (1). In its molecule, two octahedra about Ta atoms are linkedvia the shared edge [(OPrⁱ)O]. Compound1 is the first example of oxoalkoxide containing such a small number of metal atoms. Unlike the known polynuclear molecules M _n O _m (OR) _p , oxoalkoxide1 is stable in solutions; on transition to the gas phase, this compound is desolvated to form a very stable molecule Ta₂O(OPrⁱ)₈ (apparently, consisting of two octahedra with a shared edge). According to the data of mass spectrometry, analogous molecules exist in the gas phase over Ta(OAlk)₅ (Alk = Me, Et, Prⁱ, or Bu¹¹). When compound1 is heated invacuo (10^–2–10^–3 Torr), Ta(OPrⁱ)₅ is sublimated. Crystals of Ta₇O₉(OPrⁱ)₁₇ (2) were formed upon prolonged storage of solutions of1 in PrⁱOH. Heptanuclear molecule2 consists of two [Ta₄] tetrahedra with a shared vertex. These tetrahedra are additionally linked togethervia one ₃-oxo and two ₂-OPrⁱ groups. Complex2 is a representative of heptameric oxoalkoxides of a new structural type.Deceased in I995.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 125–131, January, 1996.     

New mechanism of chaos in triangular billiards

A new mechanism of weak chaos in triangular billiards has been proposed owing to the effect of cutting of beams of rays. A similar mechanism is also implemented in other polygonal billiards. Cutting of beams results in the separation of initially close rays at a finite angle by jumps in the process of reflections of beams at the vertices of a billiard. The opposite effect of joining of beams of rays occurs in any triangular billiard along with cutting. It has been shown that the cutting of beams has an absolute character and is independent of the form of a triangular billiard or the parameters of a beam. On the contrary, joining has a relative character and depends on the commensurability of the angles of the triangle with π. Joining always suppresses cutting in triangular billiards whose angles are commensurable with π. For this reason, their dynamics cannot be chaotic. In triangular billiards whose angles are rationally incommensurable with π, cutting always dominates, leading to weak chaos. The revealed properties are confirmed by numerical experiments on the phase portraits of typical triangular billiards.     

Nonlinear vortex dynamo in a rotating stratified moist atmosphere

We have found a new type of large-scale instability in a rotating stratified moist atmosphere with small-scale turbulence. The turbulence is excited by an external small-scale force with a low Reynolds number. We have constructed the theory based on the method of multiscale asymptotic expansions. The nonlinear equations for large-scale motion have been derived in the third order of the perturbation theory. We have investigated the linear instability and stationary nonlinear regimes. Solutions in the form of localized vortex structures or kinks of a new type have been obtained.     

Control of energy spread and dark current in proton and ion beams generated in high-contrast laser solid interactions

By using temporal pulse shaping of high-contrast, short pulse laser interactions with solid density targets at intensities of 2 × 10(21) W cm(-2) at a 45° incident angle, we show that it is possible to reproducibly generate quasimonoenergetic proton and ion energy spectra. The presence of a short pulse prepulse 33 ps prior to the main pulse produced proton spectra with an energy spread between 25% and 60% (ΔE/E) with energy of several MeV, with light ions becoming quasimonoenergetic for 50 nm targets. When the prepulse was removed, the energy spectra was broad. Numerical simulations suggest that expansion of the rear-side contaminant layer allowed for density conditions that prevented the protons from being screened from the sheath field, thus providing a low energy cutoff in the observed spectra normal to the target surface.