New Routes to η¹- and (η³↔η⁵)-Indenylpalladium Complexes: Synthesis, Characterization, and Reactivities

The dimer {(η³-Ind)Pd(μ-Cl)}₂ (6) reacts with t-BuNC to give the dimeric species {(η¹-Ind)(t-BuNC)Pd(μ-Cl)}₂ (10), whereas reaction with PR₃ gives the complexes (η-Ind)Pd(PR₃)Cl (R = Ph (4), Cy (7), Me (8), OMe (9)). Complexes 4 and (1-Me-Ind)Pd(PPh₃)Cl (5) can also be prepared by reacting (PhCN)₂PdCl₂ with LiInd and PPh₃. The structural characterization of complexes 4−7, 9, and 10 by ¹H and ¹³C NMR spectroscopy and single-crystal X-ray diffraction studies has allowed an analysis of the indenyl ligand's mode of coordination, both in the solid-state and in solution. Compounds 4, 6, and 7 react with PhSiH₃ in the absence of cocatalysts, whereas reaction with ethylene requires the presence of excess MAO to give polyethylene.