Dimethyl- and Diethyltin(IV) Compounds with Perfluorobiphenyl-4-Thiolate and Perfluoronaphthalene-2-Thiolate Anions: The Crystal Structure of (CH3)2Sn(C12F9S)2

Compounds (CH₃)₂Sn(C₁₂F₉S)₂ (I), (CH₃)₂Sn(C₁₀F₇S)₂ (II), and (C₂H₅)₂Sn(C₁₀F₇S)₂ (III) were synthesized. Single crystals of Iwere grown and structurally characterized using X-ray diffraction analysis (1590 reflections, R = 0.0209). The crystals are orthorhombic, a = 40.848(8) Å, b = 6.058(1) Å, c = 11.183(2) Å, V = 2767(1) ų, (calcd.) = 2.024 g/cm³, space group Pbcn, Z = 4. The structure is built from monomeric molecules. The coordination polyhedron of the Sn atom (the SnC₂S₂ core) is a distorted tetrahedron. Compounds I–III are volatile when heated in vacuo. Thermolysis of these compounds results in SnO₂ (in air) or SnS₂ (in argon).     

Silver(I) Compounds with Perfluorinated Aromatic Thiols C6F5C6F4SH,C10F7SH,and C6F5SH as Precursors for Silver Nanoparticles

Silver(I) compounds with perfluorinated aromatic thiols (4-nonafluorodiphenylthiol C₆F₅C₆F₄SH (HL¹), 2-heptafluoronaphthalenethiol C₁₀F₇SH (HL²), and pentafluorothiophenol C₆F₅SH (HL³), namely AgL¹ (I), AgL² (II), AgL³ (III), were prepared. The thermal properties of compounds I–III and the composition of thermolysis products were studied. By powder X-ray diffraction and electron microscopy, it was shown that thermolysis of compounds I–III under argon and thermolysis of compound III in air yield Ag nanoparticles.     

CdS formation upon decomposition of Cd(n-BuOCS2)2 in EtOH and DMF and the crystal structure of Cd(Ph3P)(n-BuOCS2)2 · Ph3P

The thermal decomposition of the chelate Cd(n-BuOCS₂)₂ (I) in EtOH and DMF, either in the absence or in the presence of Ph₃P, yields finely disperse CdS particles. Mixed-ligand complex Cd(Ph₃P)(n-BuOCS₂)₂ (II) has been synthesized. Cd(Ph₃P)(n-BuOCS₂)₂ · Ph₃P (III) single crystals have been grown. By X-ray crystallography, the crystal structure of III is built of [Cd(Ph₃P)(n-BuOCS₂)₂] mononuclear complex molecules and uncoordinated Ph₃P molecules, which reside inside channels formed by complex II molecules. The coordination polyhedron around a Cd atom is a tetragonal pyramid where the base is formed by the four S atoms of the two bidentate chelating ligands n-BuOCS₂⁻ and the P atom of the Ph₃P ligand is at the axial vertex. In the structure of III, there are supramolecular assemblies of two complex II molecules.     

Quantitative estimate of the helical twist in a cholesteric mesophase based on the structure parameters for the chiral molecules

Monokristallreaktiv Scientific-Production Association. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 5, pp. 146–147, September–October, 1991     

Generalized holonomy of supergravities with 8 real supercharges

We show that the generalized holonomy groups of ungauged supergravity theories with 8 real supercharges must be contained in

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, where is the generalized structure group. Here n=4ν is the number of preserved supersymmetries, so the allowed values are limited to n=0,4,8. In particular, solutions of ungauged supergravities in four, five and six dimensions are examined and found to explicitly follow this pattern. We also argue that the G-structure has to be a subgroup of this generalized holonomy group, which may provide a possible classification for supergravity vacua with respect to the number of supercharges.