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.