Direct Synthesis and Bonding Properties of the First μ2‑η2,η2‑Allyl-Bridged Diiridium Complex

The direct synthesis of the first μ2-η2,η2-allyl-bridged diiridium complex ([2]+), bearing the uncommon counterion [IrCl2(COD)]− ([3]−), is described. Both bridging moieties in [2]+, namely, allyl and acetate, are introduced in a single reaction step from [{IrCl­(COD)}2] (1) and allyl acetate. A combination of X-ray crystallography and density functional theory calculations reveals pronounced metal–allyl π-back-bonding.