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

Thorium redox chemistry is extremely scarce due to the high stability of Th-IV. Here we report two unique examples of thorium arenide complexes prepared by reduction of a Th-IV-siloxide complex in presence of naphthalene, the mononuclear arenide complex [K(OSi((OBu)-Bu-t)(3))(3)Th(eta(6)-C10H8)] (1) and the inverse-sandwich complex [K(OSi((OBu)-Bu-t)(3))(3)Th](2)(mu-eta(6),eta(6)-C10H8)] (2). The electrons stored in these complexes allow the reduction of a broad range of substrates (N2O, AdN(3), CO2, HBBN). Higher reactivity was found for the complex 1 which reacts with the diazoolefin IDipp=CN2 to yield the unexpected Th-IV 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.

Automated summary

We report two unique thorium arenide complexes prepared by reduction of a Th-IV-siloxide complex in presence of naphthalene. The stored electrons in these complexes enable the reduction of a broad range of substrates. The reactivity can be tuned by the arenide binding mode, as shown in the reaction of complex 1 with diazoolefin IDipp=CN2.