Bonding and Reactivity in Terminal versus Bridging Arenide Complexes of Thorium Acting as Th Synthons.

Thorium redox chemistry is extremely scarce due to the high stability of Th . Here we report two unique examples of thorium arenide complexes prepared by reduction of a Th -siloxide complex in presence of naphthalene, the mononuclear arenide complex [K(OSi(O Bu) ) Th(η -C H )] (1) and the inverse-sandwich complex [K(OSi(O Bu) ) Th] (μ-η ,η -C H )] (2). The electrons stored in these complexes allow the reduction of a broad range of substrates (N O, AdN , CO , HBBN). Higher reactivity was found for the complex 1 which reacts with the diazoolefin IDipp=CN to yield the unexpected Th amidoalkynyl complex 5 via a terminal N-heterocyclic vinylidene intermediate. This work showed that arenides can act as convenient redox-active ligands for implementing thorium-ligand cooperative multielectron transfer and that the reactivity can be tuned by the arenide binding mode.