X-RAY-EMISSION AND EXAFS SPECTROSCOPIC ST UDY OF COBALT COMPLEXES WITH POLYSTYRENE-POLYBUTADIENE BLOCK-COPOLYMER

The electronic and atomic structures of a metallocomplex polymer syste m obtained by interaction of a polystyrene-polybutadiene block copolym er with cobalt carbonyl, followed by vacuum annealing were studied, Th e X-ray emission spectra indicate that cobalt atoms in the metallocomp lex polymer form pi-complexes with butadiene fragments of the polymer and occur in a high-spin state. The EXAFS data show evidence that coba lt atoms in the polymer form dimers, where each metal atom interacts w ith one butadiene fragment of the block copolymer and three carbonyl g roups. The metal-metal and metal-carbon distances are determined. The thermal decomposition of the metallocomplex polymer leads to the forma tion of a phase of metallic cobalt clusters with an average diameter a bout 10 Angstrom.