Radiochemical tracer
experiments show that in the thiocyanate complex, [Co(NH3)5SCN]
[SCN]2, thermal isomerization to the isothiocyanate
salt proceeds with incorporation of anionic thiocyanate. At least 45% of the
isomerization process proceeds by a dissociative path. This contrasts with the
mechanism in water solution where isomerization occurs without exchange with
thiocyanate in solution. The result also shows the inadequacy of the generally
made assumption that isomerization in the solid state is an intramolecular
process. The chloride and thiocyanate salt were subjected to simultaneous thermogravimetric analysis and differential scanning calorimetry. The thiocyanate salt deamminates
at a much lower temperature (from 100�C) than the chloride (from 160�C), but no
process corresponding to the isomerization could be detected.
