Date of Award
1987
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Abstract
High resolution ultraviolet photoelectron spectra of substituted tungsten carbonyl derivatives have been measured. The study of the photoelectron peaks due to the tungsten 5d orbitals in the series of complexes (W(CO){dollar}{lcub}\rm\sb{lcub}n{rcub}L\sb{lcub}6-n{rcub}{rcub}{dollar}) has demonstrated that the Ligand Additivity Model holds for the systems where L are tertiary phosphine ligands. This work confirms that the splitting of the tungsten 5d orbitals observed in the photoelectron spectra can be described in terms of ligand field effects and are not dominated by relaxation effects.;The substituent effects of methyl and phenyl groups in isocyanide and tertiary phosphine ligands have been studied by photoelectron, infrared and nuclear magnetic resonance spectroscopy. The series of compounds studied, (W(CO){dollar}\sb5{lcub}\rm L{rcub}{dollar}), offered a unique opportunity for the investigation of the steric and electronic effects of the substituents, as well as for a comparison of the measurements done in the gas phase (UPS) versus those in solutions (IR and NMR). The results indicate that the phenyl substituents increase the donor ability of the phosphine and isocyanide ligands. This demonstrates that the donor ability of phosphine and isocyanide ligands cannot be explained by any single cumulative factor such as inductive effects of the substituent groups, but that solvation effects, steric effects and {dollar}\pi{dollar}-bonding effects must also be considered. A conjugative interaction of the phenyl group with the ligand is proposed to contribute to the increase in the donor ability of the ligands.;The ultraviolet photoelectron spectra of the complexes cis - (PtMe{dollar}\sb2{lcub}\rm L\sb2{rcub}{dollar}) (L = CNMe, CNPh, {dollar}{lcub}\rm PMe\sb3{rcub}{dollar}, {dollar}{lcub}\rm PMe\sb2 Ph{rcub}){dollar} have been measured. The results indicate that the donor ability of the ligands also increases when the methyl group is replaced by the phenyl group.;A comparative spectroscopic study of the series of complexes, (W(CO){dollar}{lcub}\rm \sb{lcub}n{rcub} (CNR)\sb{lcub}6-n{rcub}{rcub}{dollar}) and cis - (PtMe{dollar}\sb2{dollar}(CNR){dollar}\sb2{dollar}) (R = Me and Ph), was found to support the proposal that the {dollar}\pi{dollar}-back-bonding ability of the phenyl isocyanide ligand is variable, and depends on the metal center and on the other ligands bonded to the metal.
Recommended Citation
Dignard, Lisa Marie, "A Photoelectron Study Of The Bonding Ability Of Phosphine And Isocyanide Ligands In Organometallic Complexes" (1987). Digitized Theses. 1592.
https://ir.lib.uwo.ca/digitizedtheses/1592