Solution and Gas-Phase Reactivity of Me12Fe8- and Related Cluster Ions

The cluster ion Me12Fe8- is an unprecedented representative of organoiron species, which are of great interest because of their possible role as intermediates in iron-catalyzed cross-coupling reactions. To learn more about its behavior in solution, the possible formation of related cluster ions, and their reactivity, electrospray-ionization mass spectrometry and gas-phase experiments were performed. Me12Fe8- adopts a highly dynamic behavior in solution and disappears in the presence of the chelating ligand N, N, N', N'-tetramethylethylenediamine. Besides homoleptic Me12Fe8-, its heteroleptic analogues Me12-nFe8Phn-, n=1-5, are also accessible. Me12Fe8- undergoes iron-halogen exchange reactions with aryl halides. These substrates, as well as their alkyl counterparts, mediate the formation of new homoleptic cluster ions up to Me18Fe12-. In contrast, no evidence was found for oxidative additions or related reactions. Gas-phase fragmentation of the cluster ions results in numerous different reactions, ranging from the loss of single methyl radicals to the reductive elimination of MePh.