Thermal annealing of 51Cr(III)-doped K3[Cr(NCS)6].4H2O

Annealing reactions of chromium-51 atoms doped onto the surface of solid K3[Cr(NCS)6].4H2O were followed by means of a paired anion/cation exchange chromatographic procedure which permitted quantification of all the species: [51Cr(NCS)sub(n)(H2O)sub(6-n)]sup(3-n) (n=0-6). Both isochronal and isothermal annealing of the doped crystals revealed a progressive formation of species with more thiocyanate ligands. Analogous to a previous recoil atom study with the same compound, the principal annealed product was [51Cr(NCS)5(H2O)]2- rather than the parent species. These results are discussed in terms of a step-wise ligand-exchange process. (orig.)