Versatile Modes of Allene Bonding in the Structures of [W2(OtBu)6(C3H4)], [W2(OtBu)6(C3H4)(CO)2], and [W2(OtBu)6(C3H4)2]

The allene moiety and the W2 center in the complex 1 are parallel—this coordination is unprecedented. Addition of CO or allene to 1 yields the two other title compounds, respectively, in which an allene is η1,η3-bonded and two CO groups or an additional η2-C3H4 ligand (see formula on the right) is present.