Formation and Reactivity of Gaseous Iron‐Sulfur Clusters

The gas‐phase reactions of Fe n + clusters, n = 1−6, with COS and CS 2 have been investigated by means of Fourier‐transform ion‐cyclotron resonance mass spectrometry. Whereas CS 2 predominantly substitutes one Fe atom, COS exclusively affords multiple sulfur transfer and thus opens a synthetic route to gaseous Fe n S x + clusters. In the final products such as Fe 2 S 2 + , Fe 3 S 2 + , and Fe 4 S 4 + , the sulfur atoms appear to occupy multiple coordination sites much like in the analogous biogeneous iron‐sulfur clusters. Bracketing experiments find IE (Fe 2 S 2 ) = 7.2±0.3 eV besides providing upper limits for IE (Fe 3 S 2 ) and IE (Fe 4 S 4 ). In accordance with the low IE (Fe 2 S 2 ), Fe 2 S 2 + does not activate H 2 or small hydrocarbons and only exhibits rather limited reactivity towards more reactive substrates. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)