Sulfur nitride polymerization

In 1975, University of Pennsylvania scientists reported synthesis of polymeric sulfur nitride. 

The sulfur nitrides have been the subject of several reviews (206—208). Although no commercial appHcations have as yet been developed for these compounds, some interest was stimulated by the discovery that polythiazyl, a polymeric sulfur nitride, (SN), with metallic luster, is electroconductive (see Inorganic highpolymers) (208,209). Other sulfur nitrides are unstable. Tetrasulfur nitride is explosive and shock-sensitive. 

A. J. Banister and I. B. Gorrell, Poly(sulfur nitride) The Fkst Polymeric Metal, Adv. Mater., 10, 1415 (1998). 

Sulfur reacts with nitrogen to form polymeric sulfur nitrides (SNx) or polythiazyls. These polymers were found to have the optical and electrical properties of metals. ... 

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. 

Solid-state (topochemical) polymerization of cyclic disulfur dinitride to poly(sulfur nitride) (or polythiazyl), -fSN, occurs on standing at ambient temperature or higher [Banister and Gorrell, 1998 Labes et al., 1979 Ray, 1978]. Disulfur dinitride is obtained by sublimation of tetrasulfur tetranitride. Polythiazyl is a potentially useful material, since it behaves like a metal. It has an electrical conductivity at room temperature about the same order of magnitude as a metal like mercury and is a superconductor at 0.3°C. Polythiazyl also has high light reflectivity and good thermal conductivity. However, it is insoluble and infusible, which prevents its practical utilization. 

Banister AJ, Gorrell IB (1998) Poly(sulfur nitride) the first polymeric metal. Adv Mater 10 1415-1429... 

There is an unusual hetero chain, (SN), discovered in 1910. which did not receive detailed attention until the 1970s. Interest centers on the fact that although it is composed of atoms of two nonmetals, polymeric sulfur nitride (also called polythiazyl) has some physical properties of a metal. The preparation is from tetrasulfur tetranitnde (see page 776) ... 

Fig. 16.6 (SN), chains m one layer of polymeric sulfur nitride. [From MncDiarmid. A. G. Mikuluki. C. M. Sarnn. M. S. Russo. P. J., Cohen. M. J. Bright. A. A. Garito. A- F. Heugcr. A. J. In Compound.1/ leiih Unusual Properties. King. R. B., Ed. Advances in Chemistry Senes 150. American Chemical Society Wishmgion. DC. 1976 Reproduced with permission. ...

The following procedures give the synthesis of tetrasulfur tetranitride, disulfur dinitride, polymeric sulfur nitride, and tetrasulfur dinitride. 

For the transformation, disulfur dinitride is allowed to stand in a vacuum desiccator for ca. 30 days, after which time all the disulfur dinitride has polymerized to polymeric sulfur nitride. The progress of the reaction may easily be told by the disappearance of the characteristic smell of disulfur dinitride. The product is a dark substance with a metallic luster. 

Poly(sulfur nitride), [SN]X, possesses remarkable properties such as electrical conductivity at room temperature and superconductivity below 0.3 K see Labes MM, Love P, Nichols LF, (1979) Chem Rev 1 [SN]X is insoluble and has a polymeric structure in the solid state with interchain S—S interactions. As these interactions are crucial to the properties of the material, [SN]X is best regarded as a solid-state polymer rather than a polymeric material with discrete macromolecular chains of the type discussed in this section... 

While some of the above discussion is in the general reedm of prognostication, some mote specific comments are appropriate. It is appeuent that em increase in both the number and types of solid-state polymerization is a desirable research objective. Here, the major initial burden lies with the chemist to design (, new reactive molecular structure and appropriately oriented monomer crystal structures. Successful development of new lattice-controlled processes resulting in the availability of well-defined fully ordered mticromolecules will readily attract the more physically and theoreticedly oriented research communities. The PDA and poly (sulfur nitride) cases bear strong witness to this point. 

Acoustic Phonons of Polymeric Sulfur Nitride, (SN)x (Abstract only) 589... 

Polymeric sulfur nitride, (SN)x, was first synthesized by Burt in... 

We have determined, both experimentally and theoretically, the one-electron density of states surrounding the Fermi level in polymeric sulfur nitride, (SN)X. The experimental measurements were performed using X-ray and ultraviolet photoemission spectroscopy (XPS and UPS), while the theoretical studies employed calculations based on OPW and pseudopotential band structures of (SN)X. 

Polymeric sulfur nitride is a highly anisotropic crystalline solid in which the measured conductivity anisotropy is of... 

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