Electron spin resonance spectroscopy of Mn(CO)5 · radicals generated in the gas phase thermolysis of Mn2(CO)10

Abstract The Mn(CO) 5 · radicals from the gas-phase thermolysis of Mn 2 (CO) 10 were trapped in a co-condensed adamantane matrix at 77 K and shown to give an ESR spectrum not contaminated by signals from other paramagnetic species. The radicals were formed in a narrow range of temperatures, 342–388 K, with an optimum at 363 K. They were found to be thermally stable, and the strongly anisotropic ESR spectrum suggested that they were fixed without free rotational movement up to 213 K. The peroxo radical Mn(CO) 5 O 2 ·was trapped, either alone or together with Mn(CO) 5 ·, in the presence of trace amounts of dioxygen.