The chemistry of bulky chelating phosphines. 3. Anionic alkyl and aryl complexes of rhodium(I) and iridium(I)

Article abstract of DOI:10.1021/om00149a023

A series of thermally stable anionic dialkyl-, diaryl-, and dialkynylrhodium(I) and dialkyl-, diaryl- and dialkynyliridium(I) bis(phosphine) complexes of the general formula (dtbpe)MR₂Li(OR′₂)_x (M = Rh, Ir; dtbpe = 1,2-bis(di-tert-butylphosphino)ethane) have been prepared and characterized by ¹H, ³¹P{¹H}, and ¹³C{¹H} NMR spectroscopy. The anionic complexes are monomeric in polar and nonpolar solvents as determined by multinuclear NMR spectroscopy. Crossover experiments indicate that the complexes (dtbpe)MR₂Li(OR′₂)_x are inert with respect to exchange of their hydrocarbon ligands in solution. Protonation of (dtbpe)MR₂Li(OR′₂)_x affords either {(μ-OH)Ir(dtbpe)}₂ (H₂O) or {(μ-H)Rh(dtbpe)}₂ (i-PrOH). The latter reaction apparently proceeds via a series of protonation/reductive elimination sequences followed ultimately by a β-hydride abstraction from the coordinated alkoxide ligand. The (dtbpe)MR₂Li(OR′₂)_x complexes also act as mild alkylating agents toward transition-metal halide complexes.