Coordination chemistry of tin: Part III. The crystal structure and thermal behavior of dipotassium dimethyl-tetrafluoro-stannate dihydrate, K2[(CH3)2SnF4]·2H2O

Reaction of (CH₃)₂SnF₂ with two equivalents of KF in aqueous medium leads to the formation of the complex salt K₂[(CH₃)₂SnF₄]·2H₂O (1). Its crystal structure was determined by single-crystal X-ray diffraction. Complex 1 crystallizes in the monoclinic space group C2 (No. 5) with the lattice parameters a=9.265(1), b=7.556(1), c=7.076(1) Å; β=98.21(1)° and Z=2. The structure is characterized by the anion [(CH₃)₂SnF₄]²⁻ in which the tin atom adopts a slightly distorted octahedral coordination, with the methyl groups in trans position. The potassium cations are pentacoordinated from three fluorine atoms and the oxygen atoms of two water molecules in the form of a distorted square pyramid. In addition, the thermal behavior of the compound was studied with the aid of TG/DSC-measurements coupled with MS, revealing that the dehydration of 1 takes place at 75 °C, with an enthalpy of 57.79 kJ mol⁻¹, and that it decomposes without melting in two further endothermic steps to undetermined phases in the system KF-SnF₂-SnF₄ and free carbon (∼0.1%).     

Double-diffusive natural convection in a porous enclosure partially heated from below and differentially salted

This paper reports numerical results of two-dimensional double-diffusive natural convection in a square porous cavity partially heated from below while its upper surface is cooled at a constant temperature. The vertical walls of the porous matrix are subjected to a horizontal concentration gradient. The parameters governing the problem are the thermal Rayleigh number (Ra=100 and 200), the Lewis number (Le=0.1, 1 and 10), the buoyancy ratio (−10N10) and the relative position of the heating element with respect to the vertical centerline of the cavity (δ=0 and 0.5). The effect of the governing parameters on fluid characteristics is analyzed. The multiplicity of solutions is explored and the existence of asymmetric bicellular flow is proved when the heated element is shifted towards a vertical boundary (δ=0.5). The solutal buoyancy forces induced by horizontal concentration gradient lead to the elimination of the multiplicity of solutions obtained in pure thermal convection when N reaches some threshold value which depends on Le and Ra.     

Comment on “Debye temperature and melting point of II‐VI and III‐V semiconductors” [Cryst. Res. Technol. 45, No. 9, 920–924 (2010)]

In the present work, we have readjusted some empirical parameters obtained by Kumar et al. in their work which contains some numerical errors.     

Ising analogue to compact-star matter

By constructing an Ising analogue of compact-star matter at subsaturation density we explored the effect of Coulomb frustration on the nuclear liquid-gas phase transition. Our conclusion is twofold. First, the range of temperatures where inhomogeneous phases form expands with increasing Coulomb-field strength. Second, within the approximation of uniform electron distribution, the limiting point upon which the phase-coexistence region ends does not exhibit any critical behavior. Possible astrophysics consequences and thermodynamical connections are discussed.     

1‐Mésityl‐6‐méthyl‐3a,4‐propano‐3a,4,5,6‐tétrahydro­[1,2,4]­oxa­diazolo­[4,5‐a]­[1,5]benzo­diazépin‐5‐one

Condensation of mesitonitrile oxide with 1,5‐benzodiazepin‐2‐one leads to the title compound, C₂₃H₂₅N₃O₂. It has been established that 1,3‐dipolar cycloaddition occurs on the C4=N5 double bond of the benzodiazepin‐2‐one.     

A Multiple-Relaxation-Time Lattice-Boltzmann Analysis for Double-Diffusive Natural Convection in a Cavity with Heating and Diffusing Plate Inside Filled with a Porous Medium

Transport in Porous Media - In the present study, a multiple-relaxation-time lattice-Boltzmann method is considered to investigate double-diffusive natural convection in a cavity with heating and...