Sulfur-nitrogen chains

The simplest chain compounds of the type RS NyR are the sulfur diimides RNSNR (Section 10.4) The other known thiazyl chains are summarized in Table 14.1. They can be conveniently classified as sulfur-rich, nitrogen-rich or even-chain species. 

Chain length S-rich N-rich Even-chain 

The reactions of S-N chains have not been studied in a systematic fashion and those that have been reported are not well understood. For example, the reduction of [ArS4N3Ar]Cl (Ar = Ph, 4-MeC6H4) with silver 

ArNSNSAr from a mixture of ArNSNAr and Ar SNSNSAr. The limited data available indicate the occurrence of transformations analogous to the ring expansion or ring contraction processes observed for S-N ring systems. 

The incorporation of S-N chains between metal centres by the use of heteroaryl substituents in complexes of the type 14.7 has been proposed as a way to generate new materials that may function as molecular wires. However, the synthesis of thiazyl chains bearing metal-binding sites has yet to be achieved. 

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J. M. Rawson and J. J. Longridge, Sulfur-Nitrogen Chains Rational and Irrational Behaviour, Chem. Soc. Rev., 53 (1997). 

Although (SN)x does not react with water or acidic solutions, it slowly decomposes in alkaline solutions and it is readily oxidized. Partial bromination of (SN) or powdered S4N4 with bromine vapour yields the blue-black polymer (SNBro.4)x which has a room temperature conductivity of 2 x 10" cm . The sulfur-nitrogen chain in this... 

Table 14.1 Sulfur-Nitrogen Chains as a Function of Chain Length...

Important aspects of the coordination chemistry of binary chalcogen-nitrogen ligands include (a) the ability of metals to stabilize labile neutral and anionic binary S-N ligands, (b) the applications of metal complexes as reagents for the preparation of other S-N compounds, and (c) the possible incorporation of metals into sulfur-nitrogen chains to produce conducting materials. 

In liquid S02 or CH2C12 solution 11 inserts an SN unit into the sulfur-nitrogen chain, Ar2S3N218, to give the salt [Ar2S4N3]Cl 19 in >75% yield (93UP1). To date, no further studies have been carried out to determine whether this chain-extension reaction is more general. 

J.M. Rawson and J.J. Longridge (1997) Chemical Society Reviews, vol. 26, p. 53 - Sulfur-nitrogen chains rational and irrational behaviour . 

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