A gas‐phase study of ligand effects on the reactivity of organometallic distonic ion Fe(p‐benzyne)

Abstract

This paper reports a gas-phase study of ligand effects on the reactivity of the organometallic distonic ion Fe(p-benzyne)+·. New organometallic distonic ions are generated by introducing a benzene ligand onto the metal center of Fe(p-benzyne)+·. We were interested in whether the reactivity of the radical site would be enhanced by ‘covering’ the metal center with extra ligands, i.e. by forming (benzene)Fe(p-benzyne)+·, since, in general, attachment of ligands reduces the reactivity of the metal center. For comparison, ions formed by attaching the same ligand to Fe(o-benzyne)+ and Fe(phenyl)+ were also studied. Reacting Fe(p-benzyne)+·, Fe(o-benzyne)+ and Fe(phenyl)+ directly with benzene generates, presumably, (benzene)Fe(p-benzyne)+·, (benzene)Fe(o-benzyne)+ and (benzene)Fe(phenyl)+, respectively. With allyl iodide, isopropyl iodide and dimethyl disulfide, (benzene)Fe(p-benzyne)+· reacts differently from its even-electron isomer, (benzene)Fe(o-benzyne)+, and its phenyl analogue, (benzene)Fe(phenyl)+. Furthermore, the results from these ion-molecule reactions and collision-induced dissociation of selected product ions indicate that the charge site and the radical site of (benzene)Fe(p-benzyne)+· interact with the neutral simultaneously and that the attachment of the benzene ligand does enhance the reactivity of the radical site to some extent. Copyright­© 1999 John Wiley & Sons, Ltd.