In the reaction of C5H5Co(C3F7)[CNCH(CH3)(C6H5)] I (1a, b) with AgClO4/NH4SCN, a mixture of the N- and S-bound isomers C5H5Co(C3F7)[CNCH(CH3)(C6H5)](CNS) (2 a, b and 8 a, b) is obtained which on treatment with pentane can be transformed into (+)-C6H5Co(C3F7)[CNCH(CH3)(C6H5)](NCS) (2a). Compound 2a is stable in the solid state and in THF-solution but undergoes epimerisation and structural isomerisation in benzene or toluene solution.