OXIDATIVE ADDITION OF O-H BONDS TO IRIDIUM(I) - SYNTHESIS AND CHARACTERIZATION OF (PHENOLATO)IRIDIUM AND (CARBOXYLATO)IRIDIUM(III) HYDRIDE COMPLEXES

The reactions of alcohols, phenols, and carboxylic acids with [Ir(COD)(PMe3)3]Cl are described. Primary and secondary alcohols react with [Ir(COD)(PMe3)3]Cl to form a complex mixture of hydrido- and carbonylhydridoiridium(III) compounds. The tertiary alcohol tert-butyl alcohol reacts with [Ir(COD)(PMe3)3]Cl to form isobutylene and the iridium(III) product resulting from oxidative addition of H2O. Phenols react with[Ir(COD)(PMe3)3]Cl to yield octahedral iridium(III) compounds of the form mer-(Me3P)3Ir(OAr)(H)(CI). One such compound (Ar = 2,4-dimethylphenyl) was crystallographically characterized and was found to belong to the orthorhombic space group Pbcn with a = 13.804(2) angstrom, b = 16.517(2) angstrom, c = 22.386(4) angstrom, V = 5104.0(15) angstrom3, and Z = 2. Refinement of 226 least-squares parameters for 3404 reflections (F>4sigma(F))led to final R = 0.0425. The Ir-O distance is 2.109(5) angstrom, and the Ir-O-C angle is 130.4(5)-degrees. One molecule of dichloromethane per two molecules of iridium complex was found in the crystal lattice apparently with C-H ... Cl hydrogen bonds formed between the dichloromethane and the chloride of mer-(Me3P)3Ir(OAr)(H)(Cl). Carboxylic acids also react with[Ir(COD)(PMe3)3]Cl to yield octahedral iridium(III) compounds with the resulting complexes of the form mer-(Me3P)3Ir(OC(O)R)(H)(Cl). Crystals of the (benzoato)iridium hydride complex were found to belong to the orthorhombic space group P2(1)2(1)2(1) with a = 10.356(3) angstrom, b = 11.734 angstrom, c = 19.561(5) angstrom, V = 2377(1) angstrom3, and Z = 4. The Ir-O distance was found to be 2.123(7) angstrom. Crystals of the (salicylato)iridium hydride compound were found to crystallize in the orthorhombic space group Pbca with a = 12.508(5) angstrom, b = 13.663(3) angstrom, c = 27.502(6) angstrom, V = 4700(2) angstrom3, and Z = 8. The Ir-O distance was found to be 2.131(6) angstrom. The structural parameters for these compounds are discussed in terms of the bonding that occurs between iridium(III) and oxygen donor ligands.