Sulfur nitrides 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. 

The oxidative addition of one equivalent of X2 (X=C1, F) to S4N4 under mild conditions produces 1,5-S4N4X2.106 The structure of 1,5-S4N4C12 (32) consists of a folded eight-membered ring [d(S- -S) = 2.45 A] with the exocyclic substituents in exo,endo positions. The reaction of 32 with (Me3SiN)2S is the best route to the binary sulfur nitride S5N6 (11).42... 

Structurally characterized since 1970 and the structure of the eighth (S4N3 ) has been redetermined recently b) the first binary sulfur-nitrogen anion, S N " was isolated in 1975 and its structure was reported a year later c) the novel sulfur nitride, SjNg, was first identified in 1978 and d) although tetrasulfur dinitride, S N, has been known since 1897, the structure was not unequivocally determined until 1981... 

Sharma, B. D., and /. Donohue The Crystal and Molecular Structure of Sulfur Nitride, S4N4. Acta crystallogr. [Copenhagen] 16, 891 (1963). 

The revised version of the crystallographic FeMo-co model implies an obvious reappraisal of the synthetic structural modeling toward iron-sulfur nitride chemistry, a held that does not currently exist as such." ... 

J. L. Bredas published Ab initio SCF-FSGO study of the structure of an isolated poly (sulfur nitride), (SN)x, chain. ... 

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. 

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. 

In order to gain information on the elecronic structure of polymer sulfur nitride, (SN)X, we investigated the photoemission properties of this interesting material. The measurements were obtained on nonoriented (SN)X films using x-ray and variable ultraviolet photoemission spectroscopy (XPS and UPS) (1), (2). Table 1 shows the nitrogen and sulfur core levels in (SN)X and in neutral elements. 

In this compound and several other structurally analogous organic and inorganic compounds, the conductivity is inversely dependent on temperature over a limited temperature region, and other characteristically metal-like properties are observed. Included in this group are polymeric sulfur nitride, (SN)a , and a group of partially oxidized, square planar platinum and iridium complexes that are collectively referred to as KCP in Figure 1 both are discussed elsewhere in this volume. 

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