Synthesis, Molecular Structure, and Reactivity of Iridium(I) and Iridium(III) Complexes Formed by Coordination and C−H Activation of the Substituted Arenes C₆H₅CH₂CH₂PiPr₂ and C₆H₅OCH₂CH₂PtBu₂

The dimer [Ir(μ-Cl)(C₈H₁₄)₂]₂ (1) reacts with AgPF₆ in acetone to give the bis(acetone) adduct cis-[Ir(acetone)₂(C₈H₁₄)₂]PF₆ (2), which upon treatment with iPr₂PCH₂CH₂C₆H₅ (L¹) affords the half-sandwich-type complex [(η⁶-L¹-κ-P)Ir(C₈H₁₄)]PF₆ (3). The methoxy-bridged dimer [Ir(μ-OMe)(C₈H₁₂)]₂ (4) gives upon treatment with the phosphonium salt L¹·HBF₄ the compound [Ir(C₈H₁₂)(acetone)(L¹-κ-P)]BF₄ (5), whereas with L²·HBF₄ (L² = tBu₂PCH₂CH₂OC₆H₅) the bis(chelate) complex [Ir(C₈H₁₂)(L²-κ²-O,P)]BF₄ (6) is generated. Both 5 and 6 react with hydrogen in acetone to yield the dihydridoiridium(III) derivatives [(η⁶-L¹-κ-P)IrH₂]BF₄ (7) and [(η⁶-L²-κ-P)IrH₂]BF₄ (8), respectively. Compounds 7 and 8 react with excess ethene or propene to give the iridium(I) olefin complexes [(η⁶-L¹-κ-P)Ir(CH₂CHR)]BF₄ [R = H (9), Me (11)] and [(η⁶-L²-κ-P)Ir(CH₂CHR)]BF₄ [R = H (10), Me (12)], which in the presence of H₂ regenerate the dihydrido precursors. The reaction of 7 with 2 equiv of PhC⋮CPh affords the π-alkyne complex [(η⁶-L¹-κ-P)Ir(PhC⋮CPh]BF₄ (14) via the stilbene derivative [(η⁶-L¹-κ-P)Ir(Z-PhCHCHPh)]BF₄ (13) as an intermediate. Compound 13 can be isolated upon treatment of 11 with Z-stilbene and has been characterized crystallographically. The reactions of 7 and 11 with acetonitrile lead to the cleavage of the arene−metal bond and afford the octahedral iridium(III) complexes [IrH₂(NCCH₃)₃(L¹-κ-P)]BF₄ (15) and [IrH(C₆H₄CH₂CH₂PiPr₂-κ²-C,P)(NCCH₃)₃]BF₄ (16), respectively. Treatment of the C−H activation product 16 with H₂ yields 15. The X-ray crystal structure analysis of 16 reveals that the Ir(NCCH₃)₃ fragment possesses the fac configuration.