Thiocyanates, halogen-bonded

Fe(phen)2(NCS)2] [51]. In the solid state (Fig. 13), a characteristic halogen bond interaction takes places between the bromine atom and the sidfur atom of the thiocyanate ligand. As already observed with non-coordinated NCS anion [53], the halogen bond donor points toward the sulfur atom, perpendicular to the C-S bond, with a Br- distance 91% of the sum of the r dw-... 

Cauliez P, Polo V, Roisnel T, Llusar R, Fourmigue M (2010) The thiocyanate anion as a polydentate halogen bond acceptor. CrystEngComm 12 558-566... 

The effect of a substituent may be substantially modified by fast, concurrent, reversible addition of the nucleophile to an electrophilic center in the substituent. Ortho- and para-CS.0 and pam-CN groups have been found by Miller and co-workers to have a much reduced activating effect on the displacement of halogen in 2-nitrohaloben-zenes with methoxide ion [reversible formation of hemiacetal (143) and imido ester anions (144)] than with azide ion (less interaction) or thiocyanate (little, if any, interaction). Formation of 0-acyl derivatives of 0x0 derivatives or of A-oxides, hydrogen bonding to these moieties, and ionization of substituents are other examples of reversible and often relatively complete modifications under reaction conditions. If the interaction is irreversible, such as hydrolysis of a... 

An important area of inorganic carbon chemistry is that of compounds with C—N bonds. The most important species are the cyanide, cyanate, and thiocyanate ions and their derivatives. We can regard many of these compounds as being pseudo-halogens or pseudo-halides, but the analogies, although reasonably apt for cyanogen, (CN)2, are not especially valid in other cases. 

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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