Dinuclear coordination of a novel four-electron reduced μ-η1,η3-allene ligand with β-agostic C-H⋯Ta interaction: Direct addition of allene to (C5Me5)2Ta2(μ-X)4 (X = Cl, Br), and molecular structure of (C5Me5)2Ta2(μ-η1,η3-C3H4)(μ-Cl)Cl3

The d2-d2 organoditantalum(III) compound (C5Me5)2Ta2(μ-X)4 (X = Cl, Br) coordinates allene in an unusual alkylidene-diyl fashion to give the fluxional (C5Me5)2Ta2(μ-η1,η3-C3H4)(μ-Cl)Cl3 with an agostic interaction of one hydrogen from the formally four electron reduced allene ligand.