Oxidative addition to iridium(I) complexes

Understanding the fundamental processes underlying the activation of small molecules by metal complexes is a continuing goal of organometallic chemistry. This thesis aims to better understand the processes and interactions of small molecules with organometallic complexes.;DFT calculations were performed on an extensive series of (PH3) 2IrX complexes to investigate the thermodynamics of C-H and N-H oxidative addition. Electronic substituent effects were decomposed into their sigma and pi effects and individually parameterized; the resulting sigma X and piX parameters were used to fit the energies of oxidative addition of methane to a series of 3- and 4-coordinate Ir(I) complexes. Regression analysis indicates that oxidative addition of methane to 3-coordinate Ir(I) complexes generally is favored by a less sigma-donating ligand trans to the vacant coordination site.;DFT calculation was used to investigate the oxidative addition of chlorobenzene and fluorobenzene to pincer iridium complexes. Activation of the aryl C-H bonds proximal to the electron-withdrawing atom is favored. The kinetic barriers were calculated and correlate with the relative steric interactions in the transition state leading to the oxidative addition product.;CO stretching frequencies for a series of Ni(CO)3L complexes were calculated using DFT calculations. NBO analysis of these complexes yielded parameters that reflect the extent of backbonding in the pi* orbitals of the CO ligands and polarization of the pib orbitals of the CO ligands. The effects of a point charge on free CO were calculated.;Experimentally, reactions of small molecules with pincer iridium complexes were investigated. The kinetic barriers for olefin dissociation from (pincer)Ir(olefin) complexes were measured. The (tBuPOCOP)Ir-catalyzed olefin isomerization of 1-octene was investigated and shows an apparent 2 nd order dependence on 1 octene concentration.;A synthesis scheme for tBu3MePCP ligand was developed. While H2 did not add to tBu4PCPIr(CO), three isomers were observed when H2 was added to tBu3MePCPIr(CO), and the isomers were assigned using an isotopic labeling experiment and NMR spectroscopy.;The thermodynamic and kinetic products of tropone addition to ( tBuPCP)IrH2 were synthesized and characterized. The formation of a tropone dimer was investigated.;The product of methyl fluoride addition to (tBuPCP)IrH 2 was characterized through NMR spectroscopy, LIFDI mass spectrometry, and elemental analysis.