Ir4 cluster-based selective catalytic hydrogenation of 1,5-cyclooctadiene

[Ir4(CO)11PPh2H] 1, [Ir4(CO)8(μ3-η2-HCCPh)(μ-PPh2)2] 2, [Ir4(CO)9(μ3-η3-Ph2PC(H)CPh) (μ-PPh2)] 3 and [Ir4(CO)12] 4, were used as catalysts precursors for the hydrogenation of 1,5-cyclooctadiene (1,5-COD). Evidence for the participation of Ir4 cluster catalyst to produce a high selective hydrogenation of 1,5-COD to cyclooctene (COE) is presented.