H addition to (PCP)Ir(CO): studies of the isomerization mechanism.

Reduced steric demand of the Me4PCP pincer ligand (PCP = κ3-C6H4-1,3-[CH2PR2]2, R = Me), allows for a more open metal center. This is evident through structure and reactivity comparisons between (Me4PCP)Ir derivatives and other (R4PCP)Ir complexes (R = tBu, iPr, CF3). In particular, isomerization from cis-(R4PCP)Ir(H)2(CO) to trans-(R4PCP)Ir(H)2(CO) is more facile when R = Me than when R = iPr.

Detection of an Iridium-Dihydrogen Complex: A Proposed Intermediate in Ionic Hydrogenation.

Addition of high pressures of H to five-coordinate [(POCOP)Ir(CO)(H)]OTf [(POCOP) = κ-CH-2,6-(OP(Bu))] complexes results in observation of two new iridium-dihydrogen complexes. If the aryl moiety of the POCOP ligand is substituted with an electron withdrawing protonated dimethylamino group at the para position, hydrogen coordination is enhanced. Five-coordinate Ir-H complexes generated by addition of triflic acid to (POCOP)Ir(CO) species show an Ir-H H NMR chemical shift dependence on the number of equivalents of acid present.

Hydride & dihydrogen complexes of earth abundant metals: structure, reactivity, and applications to catalysis.

Recent developments in the chemistry of hydride and dihydrogen complexes of iron, cobalt, and nickel are summarized. Applications in homogeneous catalysis are emphasized.

Characterization of a palladium dihydrogen complex.

The preparation and isolation of the first palladium dihydrogen complex is described. NMR spectroscopy reveals a very short H-H bond length, but the hydrogen molecule is activated toward heterolytic cleavage. An X-ray crystal structure suggests that proton transfer to the (tBu) PCP (κ(3)-2,6-((t)Bu2PCH2)2C6H3) pincer ligand is possible.

Oxyfunctionalization with Cp*Ir(III)(NHC)(Me)(Cl) with O₂: identification of a rare bimetallic Ir(IV) μ-oxo intermediate.

Methanol formation from [Cp*Ir(III)(NHC)Me(CD2Cl2)](+) occurs quantitatively at room temperature with air (O2) as the oxidant and ethanol as a proton source. A rare example of a diiridium bimetallic complex, [(Cp*Ir(NHC)Me)2(μ-O)][(BAr(F)4)2], 3, was isolated and shown to be an intermediate in this reaction. The electronic absorption spectrum of 3 features a broad observation at ∼660 nm, which is primarily responsible for its blue color.