AuthorEck, Charles Paul.
AdvisorFeltham, Robert D.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractThe reaction of Pd(NO₂)₂L₂(L = P(4-Cl-C₆H₄)₃, PEtPh₂,PMePh₂) with CO was investigated. A technique was developed to analyze the gaseous products of the reaction, CO₂ and N₂O, and to quantify the molar amounts of CO₂ and N₂O evolved using infrared spectroscopy. The reaction solution was analyzed by variable temperature ultraviolet-visible spectroscopy to give evidence for at least five species in the reaction solution. The reaction with CO leads to three moles of CO₂ and one mole of N₂O per mole of Pd(NO₂)₂L₂. Less than stoichiometric amounts were observed when significant amounts of nitrosyl complexes remained in solution, as, for example, when L = PMePh₂ at low concentrations. The initial rate of CO₂ evolution is dependent upon the concentration of the starting material and precedes N₂O evolution. The rate of N₂O evolution depends upon the phosphine ligand and the palladium concentration with no N₂O being evolved at low Pd(NO₂)₂L₂ concentrations. The observed initial rate constant for the disappearance of Pd(NO₂)₂ (PMePh₂)₂ is 0.04642 min⁻¹ (25°C, 1.1 x 10⁻⁴ M), and the observed initial rate constant for the evolution of CO₂ is 0.001963 min⁻¹ (25°C, 0.95 x 10⁻⁴ M), indicating the initial formation of the five-coordinate intermediate, PdCO(NO₂)₂L₂, prior to CO₂ evolution. This intermediate subsequently evolves CO₂ and forms the nitro-nitrosyl complex, Pd(NO₂)(NO)L₂. A third intermediate was identified as the five-coordinate PdCO(NO₂)(NO)L₂. This third species also decomposed, liberating a second mole of CO₂ and producing the dinitrosyl complex, Pd(NO)₂L₂. It is proposed that the dinitrosyl complex subsequently undergoes bimolecular reactions leading to the evolution of the third mole of CO₂ and to the formation of N₂O.