Isolation, bonding and reactivity of a monomeric stibine oxide

In contrast to phosphine oxides and arsine oxides, which are common and exist as stable monomeric species featuring the corresponding pnictoryl functional group (Pn=O/Pn(+)–O(−); Pn = P, As), stibine oxides are generally polymeric, and the properties of the unperturbed stiboryl group (Sb=O/Sb(+)–O(−)) remain unexplored. We now report the isolation of the monomeric stibine oxide, Dipp(3)SbO (where Dipp = 2,6-diisopropylphenyl). Spectroscopic, crystallographic and computational studies provide insight into the nature of the Sb=O/Sb(+)–O(−) bond. Moreover, isolation of Dipp(3)SbO allows the chemistry of the stiboryl group to be explored. Here we show that Dipp(3)SbO can act as a Brønsted base, a hydrogen-bond acceptor and a transition-metal ligand, in addition engaging in 1,2-addition, O-for-F(2) exchange and O-atom transfer. In all cases, the reactivity of Dipp(3)SbO differed from that of the lighter congeners Dipp(3)AsO and Dipp(3)PO. [Image: see text]