Chalcogen-nitrogen compounds

Polymer and chain formation is another property of chalcogen-nitrogen compounds that distinguishes them from their oxygen analogues. In addition to the unique, superconducting poly(sulfur nitride) (SN) (1.24) (Section 14.2), a variety of poly(thiazyl) chains such as RS5N4R (1.25) (Section 14.3) have been characterized. Interest in these chains stems from their possible use as models for the behaviour of (SN) and as components in molecular materials, e.g., as molecular wires. 

Chalcogen-Nitrogen Compounds with the Chalcogen in Higher Oxidation States... 

Reactions of ionic or covalent azides with chalcogen halides or, in the case of sulfur, with the elemental chalcogen provide an alternative route to certain chalcogen-nitrogen compounds. Eor example, the reaction of sodium azide with cyclo-Sa in hexamethylphosphoric triamide is a more convenient synthesis of S7NH than the S2CI2 reaction (Section 6.2.1). Moreover, the azide route can be used for the preparation of 50% N-enriched S7NH. 

This chapter will provide an overview, illustrated with recent examples, of some applications of the most commonly used physical methods for the characterization of chalcogen-nitrogen compounds. 

The structures of chalcogen-nitrogen compounds are frequently unpredictable. For example, the reactions of heterocyclic systems often result in substantial reorganization of their structural frameworks, e.g. ring expansion or contraction. The formation of acyclic products from ring systems (or vice versa) is also observed. 

Electron diffraction studies provide valuable information about structures in the gas phase. Consequently, this method is important for chalcogen-nitrogen compounds that are liquids or gases at room temperature. The application of this technique has provided evidence for the monomeric structures of the 1,2,3,5-dithiadiazolyl radical [CEsCNSSN] (3.3) and the 1,3,2-dithiazolyl [CEsCSNSCCEs] (3.4), a... 

Specific structural information for various classes of chalcogen-nitrogen compounds will be discussed in the appropriate chapters. 

Electrochemical methods may also be used in the synthesis of chalcogen-nitrogen compounds. For example, the electrochemical reduction of salts of the [SsNs]" cation (Section 5.3.9) in SO2 or CH2CI2 at low temperatures produces microcrystals of the superconducting polymer (SN). ... 

A variety of physical techniques are used for the characterization of chalcogen-nitrogen compounds. 

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