Chalcogen chains

Scheme 5-42. [2]Ferrocenophanes containing a chalcogen chain link.

Golovchak R., Shpotyuk 0., Kozdras A., Vicek M., Bureau B., Kovalskiy A., and Jain H., Long-term physical ageing in As-Se glasses with short chalcogen chains./. Phys. Condens. Matter, 20, 245101/1-245101/7 (2008). 

Monoorganyl derivatives of chalcogen chains are mostly still named radicofunctionally as. ..ylhydropolychalcogenides (exception . ..yl hydroperoxides) although systematically they are to be perceived as ylpoly-chalcogenanes. 

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. 

TI4SCI4 and T SeCh melt at 440 and 442°C, respectively. They can be distilled between 650 and 700°C without decomposition. They are insoluble in H2O and organic solvents, but soluble in aqueous alkaline solutions. With cone, acids, decomposition takes place. The electric conductivity has been determined to be 1.4-10 and 2.1-10 fl cm for TI4SCI4 and TUSeCU, respectively. The probable structural formula is Tl3(TlCl4Y). The compounds thus, presumably, consist of Tli,4Cl4,4Y2/8 octahedra that are interconnected by the chalcogen atoms to linear chains (321). 

The effect shown in Fig. 9 is a result of the bond-bond interaction which is a characteristic feature for chains and rings of two-valent chalcogen atoms. It can also be recognized from the relatively large bond interaction force constants fir of such compounds. The stretching force constants /r(SS) of polysulfur compounds depend on the SS bond distances as shown in Fig. 10. The data used in this figure include several excited electronic states of the S2 molecule as well as the disulfide anion and a number of sulfur homocycles [77]. 

J. Beck, Rings, cages and chains - the rich structural chemitry of the polycations of the chalcogens. Coord. Chem. Rev. 163 (1997) 55. 

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. 

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