Coupling reactions of Fe(benzyne)+ and Fe(naphthyne)+ in the gas phase

Abstract

The gas phase ion–molecule reactions of Fe(benzyne)+ and Fe(naphthyne)+ with acetylene, allene, ethene, butadiene, buckminsterfullerene and cyclopropane are studied using Fourier transform ion cyclotron resonance mass spectrometry. In a previous study we proposed that the reaction of Fe(benzyne)+ with ethene proceeds by a mechanism in which a multiple carbon–carbon bond couples with a metal–carbon bond of Fe(benzyne)+ to form new carbon–carbon and metal–carbon bonds. In this study we include the reactions of Fe(naphthyne)+ in order to test the generality of this mechanism and to observe the non-metallic products formed in these reactions. Fe(benzyne)+, for example, reacts with acetylene to yield Fe+ and C6H4C2H2, exclusively. In contrast, the reaction of Fe(naphthyne)+ with acetylene produces Fe+, C10H6C2H2+ and a metallacyclic product F &45BITw;e−C10H6−C &45SROz; 2H2+. This lends support that the neutral product formed in the reaction of Fe(benzyne)+ with acetylene is an intact C6H4C2H2. Similarly, Fe(naphthyne)+ reacts with ethene to form a metallacyclic product F &45BITw;e−C10H6−C &45SROz; 2H4+. In the reaction with C60, Fe(naphthyne)+ is observed to yield the C60 derivatives C60C10H6+ and F &45BITw;e−C10H6−C &45SROz; 60+. These gas phase ion–molecule coupling reactions are analogous to the condensed phase coupling reactions of metallobenzynes with molecules containing multiple bonds. © 1997 John Wiley & Sons, Ltd.