UBC Theses and Dissertations
Photoelectron spectroscopy of unstable molecules : multiply bonded nitrogen compounds MacDonald, Charles Bruce
As part of a continuing investigation of the electronic structure of unstable and transient molecules, the vacuum ultra—violet photoelectron spectra of thirteen compounds ( CH₂=NCH₃, CH₃CH=NH, H₂C(CN ) ₂ , Cl₂C(CN}₂, Br₂C(CN)₂, ClNCO, BrNCO, INCO, ClNNN, BrNNN, ClSCN, BrSCN, and (SCN)₂) have been obtained. The spectra have been assigned using vibrational analysis of the band shapes, molecular orbital theory, comparisons to similar and isoelectronic molecules, and variations of relative band cross-sections with photon energy. All the molecules studied contain multiply bonded nitrogen, and most involve pseudohalogen functional groups. This work provides the first gas phase detection and spectroscopic results for several halogan pseudohalide molecules. The azide, isocyanate, and thiocyanate functional groups are investigated by following the perturbation of an off-axis halogen atom. The effect of replacing a halogen with a cyano group is also demonstrated in several instances. Correlation of photoelectron spectra of cyano molecules, with their halogen analogues is shown to be useful in interpreting the results. Small, substituted imines belong to a group of molecules of current astrophysical interest. High yield preparative routes for CH₂=NCH₃ and CH₃CH=NH have been developed, and the molecules studied by photoelectron spectroscopy.
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