Temporal accuracy analysis of phase change convection simulations using the JFNK‐SIMPLE algorithm

The incompressible Navier–Stokes and energy conservation equations with phase change effects are applied to two benchmark problems: (1) non‐dimensional freezing with convection; and (2) pure gallium melting. Using a Jacobian‐free Newton–Krylov (JFNK) fully implicit solution method preconditioned with the SIMPLE (Numerical Heat Transfer and Fluid Flow. Hemisphere: New York, 1980) algorithm using centred discretization in space and three‐level discretization in time converges with second‐order accuracy for these problems. In the case of non‐dimensional freezing, the temporal accuracy is sensitive to the choice of velocity attenuation parameter. By comparing to solutions with first‐order backward Euler discretization in time, it is shown that the second‐order accuracy in time is required to resolve the fine‐scale convection structure during early gallium melting. Qualitative discrepancies develop over time for both the first‐order temporal discretized simulation using the JFNK‐SIMPLE algorithm that converges the nonlinearities and a SIMPLE‐based algorithm that converges to a more common mass balance condition. The discrepancies in the JFNK‐SIMPLE simulations using only first‐order rather than second‐order accurate temporal discretization for a given time step size appear to be offset in time. Copyright © 2007 John Wiley & Sons, Ltd.     

A facile high-yield solvothermal route to tin phosphide Sn4P3

An effective method of synthesis of tin phosphide Sn₄P₃ starting from metallic tin and amorphous red phosphorus by a low-temperature (200 °C) solvothermal reaction in ethylenediamine is offered. The key parameters of this process - duration, temperature, and the ratio of initial components (Sn/P) are studied. The structure, phase composition, and morphology of the products are investigated using powder X-ray diffraction and scanning electron microscopy. Different synthetic ways for tin phosphide are discussed and compared with the proposed one. The mechanism of solvothermal preparation of tin phosphide in ethylenediamine is discussed. It is shown that the proposed solvothermal method opens up the possibility of preparing other metal-rich phosphides.     

Three‐Component Gallium(III)‐Promoted Addition of Halide Anions and Acetylenes to Donor–Acceptor Cyclopropanes

A new strategy for the three‐component addition of halide anions and acetylenes to donor–acceptor cyclopropanes (DACs) is presented. This reaction, which occurs with high E selectivity, is promoted by gallium(III) salts and based on the 1,2‐zwitterionic reactivity of DACs. It opens up a new group of processes involving DACs. The reaction occurs readily with a broad range of substrates and is tolerant of various functional groups. This methodology makes it possible to assemble highly functionalized vinyl halides, which are very convenient building blocks in organic synthesis. A possible mechanism of this reaction and its stereochemical aspects are discussed in detail.     

L3C3P3: Tricarbontriphosphide Tricyclic Radicals and Cations Stabilized by Cyclic (alkyl)(amino)carbenes

Alkynes usually oligomerize to give rings with a conjugated π‐electron system. In contrast, phosphaalkynes, R?C≡P, frequently give compounds with polycyclic structures, which are thermodynamically more stable than the corresponding π‐conjugated isomers. The syntheses of the first C₃P₃ tricyclic compounds are reported with either radical or cationic ground states stabilized by cyclic (alkyl)(amino)carbenes (CAACs). These compounds may be considered as examples of tricarbontriphosphide coordinated by carbenes and are likely formed via trimerization of the corresponding mono‐radicals CAAC‐CP^.. The mechanism for the formation of these tricarbontriphosphide radicals has been rationalized by a combination of experiments and DFT calculations.     

Ba3P3I2 und Ba5P5I3: Stufenweise Oxidation von Bariumphosphid mit Iod

Ba₃P₃I₂ and Ba₅P₅I₃: Stepwise Oxidation of Barium Phosphide with Iodine The novel compounds Ba₃P₃I₂ and Ba₅P₅I₃ were obtained by the reaction of barium phosphide with iodine. The air and moisture sensitive compounds crystallize in new structure types: Ba₃P₃I₂ (oP32; Pnma; a = 1719.5(4) pm; b = 462.4(2) pm; c = 1427.2(4) pm; Z = 4; R(F)_N′ = 0.067 (N′(hkl) = 2667), Ba₅P₅I₃ (mC52; C2/m; a = 4266.4(13) pm; b = 456.3(2) pm; c = 943.1(3) pm; ß = 92.20(3)°; Z = 4; R(F)_N′ = 0.040 (N′(hkl) = 3909). Both can be described as double salts of a hypothetic Zintl Phase ('Ba₂P₃' or 'Ba₇P₁₀') and a halide (BaI₂). Characteristic structural features are P₃ and P₄ chains, corresponding to Ba₃[P₃]I₂ and Ba₁₀[P₃]₂[P₄]I₆, respectively. The bonding characteristics will be interpreted on the basis of the structure and the physical properties.     

Aqueous-solution growth of GaP and InP nanowires: a general route to phosphide, oxide, sulfide, and tungstate nanowires

A general synthetic route has been developed for the growth of metal phosphide, oxide, sulfide, and tungstate nanowires in aqueous solution. In detail, cetyltrimethylammonium cations (CTA(+)) can be combined with anionic inorganic species along a co-condensation mechanism to form lamellar inorganic-surfactant intercalated mesostructures, which serve as both microreactors and reactants for the growth of nanowires. For example, GaP, InP, gamma-MnO(2), ZnO, SnS(2), ZnS, CdWO(4), and ZnWO(4) nanowires have been grown by this route. To the best of our knowledge, this is the first time that the synthesis of GaP and InP nanowires in aqueous solution has been achieved. This strategy is expected to extend to grow nanowires of other materials in solution or by vapor transport routes, since the nanowire growth of any inorganic materials can be realized by selecting an appropriate reaction and its corresponding lamellar inorganic-surfactant precursors.     

HfNixP – Intercalation of Ni into the Three-Dimensional Compound HfP

The new compound HfNi_xP (x = 0.426(1), crystal structure: P6₃/mmc, a = 3.737(1) Å, c = 12.666(2) Å, V = 153.21(7) ų) has been prepared by arc-melting of HfP with nickel and subsequent annealing at 1400°C. Its crystal structure can be considered as a filled HfP structure, with the Ni atoms inserted into the trigonal prismatic voids of the Hf sublattice. Since the neighboring trigonal Hf₆ prisms are centered by P atoms, each of the three rectangular faces of the Hf₆Ni prism is capped with one P atom. Altogether, the structure of HfNi_xP consists of alternating layers of Hf atoms with the packing sequence AABB . One P and the Ni position are situated between the eclipsed Hf layers, whereas the other P site between the A and B layers is surrounded by six Hf atoms in a staggered arrangement. The calculated density of states (Extended Hückel approximation) points to metallic conductivity; threedimensional metallic behavior is assumed because of the Hf–Hf bonding interactions along all three directions.     

Trimethylaminedichlorogailane (Cl2Ga · NMe3)2 with the Ga-Ga intermetallic bond

The reaction of GaH₃ · NMe₃ with ClPBu^t ₂ in ether occurs through the exchange of ligands followed by reduction of Ga³⁺ to Gaz+ to yield (GaCl₂ · NMe₃)₂. X-ray structural analysis demonstrated that gallium atoms in this compound form a direct metal-metal bond with the length of 2.421 Å.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 2078–2081, August, 1996.