Oxidative addition of N-H and O-H bonds to iridium : developing active catalysts for N-H and O-H additions to unsaturates
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The oxidative addition of the N-H bond of both heterocyclic and acyclic amines and the O-H bond of phenols, water and carboxylic acids to iridium(I) trimethylphosphines complexes was studied and the reactivity of the resulting hydrido amido-, aryloxo- and carboxylato iridium(III) complexes was investigated. Oxidative addition of the N-H bond of pyrrole, indole, 3-methylindole, 7-azaindole, carbazole and aniline to [Ir(COD)(PMe3)3]CI (la) (COD = 1,5-cyclooctadiene) produces merIr( NR2)H(PMe3)3CI (2a-f) complexes. That these amines were bound to iridium through an Ir-N bond was established by 1H, 31P and 13C NMR spectroscopy, IR spectroscopy, C-H analyses and single crystal x-ray diffraction. Similarly, oxidative addition of the O-H bond of phenol, p-cresol, 3,5-dimethylphenol, and water to [Ir(COD)(PMe3)3]CI (la) produces mer-Ir(OR)H(PMe3)3C1 (5a-c and 6) which were characterized by 1H, 3131P and 13C NMR spectroscopy, C H analyses and single crystal x-ray diffraction. A preliminary study of the reactivity of both the amido and aryloxo complexes suggests that because of the increased electron affinity of the heteroatoms involved (N or 0), there is high electron density at the heteroatoms in these complexes and therefore the M-N or M-O bond can heterolyze more easily than M-C bonds. This increased tendency of the M-N or M-O bond to heterolyze leads to decomposition reactions when attempts are made to open up a coordination site at the metal center by removing the chloride ligand.
- Doctoral Dissertations