[Ir2(μ‐CH2)(CO)4 Me2PCH2P(Me2)2][CF3SO3]2, an Unprecedented Electrophilic Methylene Complex; H⊖ Addition to Prepare a Bridging Methyl Complex

The μ-CH2 bridge of 1 is attacked nucleophilically and not—as usually the case—electrophilically. This dramatic difference between 1 and Herrmann carbene complexes might be due to the combination of dication character and four CO ligands, which reduces the electron density at the metal center available for the free p orbital of the CH2 ligand. Complex 1 is formed as shown in Equation (a) and reacts, for example, with the H⊖ donor HBsBu to give the methyl-bridged complex [Ir2(CO)2(μ-CH3)L2]X, X  CF3SO3.