METHANE ACTIVATION BY RHODIUM CLUSTER ARGON COMPLEXES

Rhodium cluster argon complexes Rhn+Arm are produced by laser vaporiza tion followed by supersonic expansion, stored in an FT-ICR mass spectr ometer, and their reactions with methane investigated. Ligand exchange reactions are observed, in which up to three argon atoms are replaced by methane. In addition, the solvated rhodium dimer and trimer cation s are found to dehydrogenate methane. The efficiency of the dehydrogen ation depends on the number of argons, with only the dimer exhibiting this reaction without ligands. This dependence of methane activation o n the size of the cluster and number of ''solvent'' argon atoms is dis cussed, and compared with heterogenous catalysis on bulk surfaces, whe re activity and selectivity are controlled by pressure and temperature .