Development of Late Transition Metal Catalysts for the Transformation of Olefins

Citation

Li, Robert Tan (1997) Development of Late Transition Metal Catalysts for the Transformation of Olefins. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/h7n7-w490. https://resolver.caltech.edu/CaltechTHESIS:07232025-205751565

Abstract

Chapter 1 describes the syntheses and reactivities of a series of IrCl(CO)(PR₃(ƞ²-3,3-diphenylcyclopropene) complexes (PR₃ = PMe₃, PMe₂Ph, PMePh₂, PEt₃). In addition, it describes a subsequent reaction of IrCl(CO)(PMe₃)₂(ƞ²- 3,3-diphenylcyclopropene) in the presence of excess IrCl(CO)(PMe₃)₂. Spectroscopic data support the formation of an iridacyclobutene as part of a bimetallic complex where the iridacyclobutene moiety is stabilized by ƞ²-coordination to IrCl(CO)(PMe₃)₂. The mechanism of this reaction was studied by kinetic measurements and isotopic labeling studies where these studies support formation of this bimetallic complex by direct insertion of IrCl(CO)(PMe₃)₂ into the C-C σ-bond of the cyclopropene moiety.

Chapter 2 describes the reactions of the iridium dimer, [Ir(COD)Cl]₂, with 3,3- diphenylcyclopropene to form the bimetallic vinylcarbene complex [Ir(COD)Cl]₂=C-C= CPh₂), and examines the activity of this complex in ring-opening metathesis polymerization (ROMP). This chapter also describes the subsequent reaction of [Ir(COD)Cl]₂(=C-C=CPh₂) with AgO₂CCX₃ (X = F and H) to form [Ir₂(COD)₂Cl(O₂CX₃)](=C-C=CPh₂) and describes their reactivity in ROMP.

Chapter 3 describes the synthesis of Ir and Rh vinylcarbene complexes and examines their activities in olefin metathesis and olefin cyclopropanation. The Ir vinylcarbene appears to be active solely in olefin metathesis and the Rh vinylcarbene appears to be active solely in olefin cyclopropanation. In addition, this chapter investigates the oxidation state effects in the Rh-mediated cyclopropanation reaction by examining the affinities of the Rh complexes toward olefins as the oxidation state of the Rh metal is increased.

Chapter 4 describes the synthesis of salicylaldimine complexes of Ni(II)-aryls and their reactivity in ethylene polymerization. The effects of varying sterics and electronics of the salicyclaldimine ligand is discussed. Bulky ligands which block the axial faces of the Ni(II) square planar complexes, and provide steric bulk in the plane of the Ni(II) square planar complex, are particularly effective in providing active ethylene polymerization catalysts that produce linear polymers with high molecular weight.

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