EXAFS study of the structure of desolvated cluster compounds of Re and Mo with cyanide and thiocyanate ligands

This paper reports on EXAFS and XANES studies of structural changes in comp lex compounds (H3O)(2)Co-3[Re6Se8(CN)(6)](2). 14.5H(2)O, Cs2Co[Re6S8(CN)(6) ]. 2H(2)O, and Co(DMF)(6)[Mo6Br8(NCS)(6)] containing the octahedral cluster anions of rhenium [Re6X8(CN)(6)](4-) (X = S, Se) or molybdenum [Mo6Br8(NCS )(6)](2-), induced by vacuum annealing at temperatures of up to 250 degrees C. According to EXAFS and XANES data, the complex cluster anions do not und ergo any pronounced changes during annealing. The parameters of the local e nvironment of the cobalt cations have been determined. Structural models of the environment of the cations in various compounds after desolvation have been constructed For Co(DMF)(6)[Mo6Br8(NCS)(6)], vacuum annealing at 250 d egreesC leads to a complete removal of DMF and formation of a new compound, Co[Mo6Br8(NCS)(6)], in which the cobalt atoms are coordinated by four sulf ur atoms of the SCN groups.