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Reactions of the Ir^Vhydride [^MeBDI^Dipp]IrH₄{BDI=(Dipp)NC(Me)CH(Me)CN(Dipp); Dipp=2,6‐iPr₂C₆H₃} with E[N(SiMe₃)₂]₂(E=Sn, Pb) afforded the unusual dimeric dimetallotetrylenes ([^MeBDI^Dipp]IrH)₂(μ₂‐E)₂in good yields. Moreover, ([^MeBDI^Dipp]IrH)₂(μ₂‐Ge)₂was formed in situ from thermal decomposition of [^MeBDI^Dipp]Ir(H)₂Ge[N(SiMe₃)₂]₂. These reactions are accompanied by liberation of HN(SiMe₃)₂and H₂through the apparent cleavage of an E−N(SiMe₃)₂bond by Ir−H. In a reversal of this process, ([^MeBDI^Dipp]IrH)₂(μ₂‐E)₂reacted with excess H₂to regenerate [^MeBDI^Dipp]IrH₄. Varying the concentrations of reactants led to formation of the trimeric ([^MeBDI^Dipp]IrH₂)₃(μ₂‐E)₃. The further scope of this synthetic route was investigated with group 15 amides, and ([^MeBDI^Dipp]IrH)₂(μ₂‐Bi)₂was prepared by the reaction of [^MeBDI^Dipp]IrH₄with Bi(NMe₂)₃or Bi(OtBu)₃to afford the first example of a “naked” two‐coordinate Bi atom bound exclusively to transition metals. A viable mechanism that accounts for the formation of these products is proposed. Computational investigations of the Ir₂E₂(E=Sn, Pb) compounds characterized them as open‐shell singlets with confined nonbonding lone pairs at the E centers. In contrast, Ir₂Bi₂is characterized as having a closed‐shell singlet ground state.

 

Cationic iron complexes [Cp*( i Pr 2 MeP)FeH 2 SiHR] + , generated and characterized in solution, are very efficient catalysts for the hydrosilation of terminal alkenes and internal alkynes by primary silanes at low catalyst loading (0.1 mol%) and ambient temperature. These reactions yield only the corresponding secondary silane product, even with SiH 4 as the substrate. Mechanistic experiments and DFT calculations indicate that the high rate of hydrosilation is associated with an inherently low barrier for dissociative silane exchange (product release). 

A cationic nickel complex of the bis(8-quinolyl)(3,5-di- tert -butylphenoxy)phosphine (NPN) ligand, [(NPN)NiCl] + , is a precursor to efficient catalysts for the hydrosilation of alkenes with a variety of hydrosilanes under mild conditions and low catalyst loadings. DFT studies reveal the presence of two coupled catalytic cycles based on [(NPN)NiH] + and [(NPN)NiSiR 3 ] + active species, with the latter being more efficient for producing the product. The preferred silyl-based catalysis is not due to a more facile insertion of alkene into the Ni–Si ( vs. Ni–H) bond, but by consistent and efficient conversions of the hydride to the silyl complex.