Facile oxidative addition of O2 and S8 by an indium bis(carbene) analogue.

The oxidative addition of oxygen towards an indium bis(carbenoid) yields an almost planar In4O2 ring, an isovalence-electronic analogue of dioxane, in which the indium is in the formal oxidation state +ii. The weaker oxidant sulfur, however, yields an eight-membered ring in a deck-chair conformation containing four indium(iii) centres and four sulfides in an alternating fashion. According to DFT calculations, this reactivity difference originates from kinetic rather than thermodynamic reasons. When the reaction with S8 is performed with the in situ generated bis(carbenoid), a β-diketimine (NacNac) incorporating an S4-chain bridging the two γ-carbon atoms of each NacNac unit is derived.