Selenocyanates sulfur compounds

Thousands of compounds of the actinide elements have been prepared, and the properties of some of the important binary compounds are summarized in Table 8 (13,17,18,22). The binary compounds with carbon, boron, nitrogen, siUcon, and sulfur are not included these are of interest, however, because of their stabiUty at high temperatures. A large number of ternary compounds, including numerous oxyhaUdes, and more compHcated compounds have been synthesized and characterized. These include many intermediate (nonstoichiometric) oxides, and besides the nitrates, sulfates, peroxides, and carbonates, compounds such as phosphates, arsenates, cyanides, cyanates, thiocyanates, selenocyanates, sulfites, selenates, selenites, teUurates, tellurites, selenides, and teUurides. 

Thiocyanate groups can be linked to tellurium via the nitrogen or sulfur atoms. In view of this uncertainty, cyanates, thiocyanates, and selenocyanates are discussed together under diorgano dinitrogen compounds (p. 637). 

The thiocyanate ion is sometimes regarded as a resonance hybrid of the two structures S—CsN and S—C=N Although organic compounds presumably related to each of the forms (of types R—S—(>s=N and R—N=C S) are known, the Raman spectra of solutions of ionic thiocyanates have been interpreted to show the presence of a feN link and the absence of a 0=S link, thus favoring the triple-bonded structure. Except for the ammonium salt, best made by heating ammonium dithio-carbamate (p. 236), ionic thiocyanates are best prepared by treatment of sulfur with the appropriate cyanide, either in solution or in fused state. (Selenocyanates may be prepared from selenium and ionic cyanides in the same way.)... 

There are no examples of xenon bonded to sulfur or selenium and few for the halogens. The reported compounds involve the thiocyanate and selenocyanate ligands acting as pseudohalides, in the anions I(SCN)i and I(SeCN)2, for which IR and Raman spectra show the thiocyanate to have a linear S—I—S arrangement but give no definitive results for the selenocyanate, and two examples with more complex thio ligands for which crystal structures have been determined. 

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