Sulfur solid structures

Sulfur nitride polymers [-(-S = N-)-], which have optical and electrical properties similar to those of metals, were first synthesized in 1910. These crystalline polymers, which are super-conducive at 0.25 K, may be produced at room temperature using the solid state polymerization of the dimer (S2N2). A dark blue-black amorphous paramagnetic form of poly(sulfur nitride) (structure 11.30) is produced by quenching the gaseous tetramer in liquid nitrogen. The polymer is produced on heating the tetramer to about 300°C. 

Besides solid-fluid equilibria, some pure materials can exist in more than one stable solid structure, giving rise to solid-solid equilibria. Examples include equilibria between the fee and bcc forms of iron, equilibria between rhombic and monoclinic sulfur, and equilibria among the many different phases of ice. Such solid-solid phase transitions are accompanied by a volume change and a latent heat, and these two quantities are related through the Clapeyron equation (8.2.27). When a pure material can undergo solid-solid phase transitions, then the substance usually exhibits multiple triple points. Besides the usual solid-vapor-liquid point, the pure substance might also exist in solid-solid-liquid or solid-solid-solid equilibria. Several such triple points occur in water, caused by equilibria involving various forms of ice [13]. 

As discussed later, work in the United States has also led to formulas based largely on sulfur dioxide measurements U.S. investigators are also trying to account for the effect of differences in shape (e.g., see Fig. 2.6, Tables 2.10 and 2.13), while Van Eijnsbergen also comments on the effect of orientation in solid structures in certain circumstances (Table 2.14). Effects of time of day (Table 2.15) are not of significance under practical conditions characterized by continuing exposure. 

The 1,5-isomers 13.3 (E = S) are colourless, air-stable solids. They are prepared by the cyclocondensation reaction of R2PN2(SiMe3)3 with sulfur dichloride or thionyl chloride. A similar cyclocondensation process, using a mixture of SeCU and Sc2Cl2 as a source of selenium, produces a mixture of the isomers 13.2 and 13.3 (E = Se, R = Ph). The structures of 13.3 (E = S, R = alkyl, aryl) are folded eight-membered rings with a cross-ring S S distance of ca. 2.50 This structural... 

The Structure of AS2S5 is unknown. It is said to be formed as a yellow solid by passing a rapid stream of H2S gas into an ice-cold solution of an arsenate in cone HCl slower passage of H2S at room temperature results in reduction of arsenate to arsenite and consequent precipitation of AS2S3. It decomposes in air above 95° to give AS2S3 and sulfur. 

The product is a black-brown solid that is very sensitive to oxygen. The same cation can be obtained by oxidation of S4N4 with AsFs and is unusual in being the only sulfur-nitrogen (paramagnetic) radical that has been obtained as a stable crystalline salt. X-ray diffraction analysis shows the structure to be a planar 5-membered ring with approximate... 

The ESR spectra of a large variety of sulfonyl radicals have been obtained photolytically in liquid phase over a wide range of temperature. Some selected data are summarized in Table 2. The magnitudes of hyperfine splittings and the observations of line broadening resulting from restricted rotation about the C—S bond have been used successfully in conjunction with INDO SCF MO calculations to elucidate both structure and conformational properties. Thus the spin distribution in these species is typical of (T-radicals with a pyramidal center at sulfur and in accord with the solid-state ESR data. 

In the solid state, sulfur is sometimes found in rings of six atoms, (a) Draw a valid Lewis structure for Sb. (b) Is resonance possible in S6 If so, draw one of the resonance structures. 

If the principal cohesive forces between solute molecules are London forces, then the best solvent is likely to be one that can mimic those forces. For example, a good solvent for nonpolar substances is the nonpolar liquid carbon disulfide, CS2-It is a far better solvent than water for sulfur because solid sulfur is a molecular solid of S8 molecules held together by London forces (Fig. 8.19). The sulfur molecules cannot penetrate into the strongly hydrogen-bonded structure of water, because they cannot replace those bonds with interactions of similar strength. 

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