<p> Under 248 nm laser flash photolysis, the photodecomposition of 1,3,4-trimethyl-1-phenyl-1-germacyclopent-3-ene (28) in dry, deoxygenated hexane solution at 23 °C leads to the prompt formation of two transient species: phenylmethylgermylene (29) and its Ge=Ge doubly bonded dimer, 1,2-dimethyl-1 ,2-diphenyldigemene (30). The formation of 29 proceeds in high chemical yield as shown by the results of steady state trapping experiments with methanol and isoprene. The transient assigned to 29 exhibits λmax = 490 nm and decays with second-order kinetics (τ ~ 2 μs). The second transient, which is formed from the
latter, is assigned to digermene 30 and exhibits λmax = 420 nm and a lifetime, τ ~ 8 μs.
The assignments are based on comparisons to the spectra of other simple germylenes, such as dimethyl-, diphenyl and dimesitylgermylene as well as on the pattern of reactivity with trapping reagents in solution at room temperature.</p> <p> Reactions studied include N-H, O-H and Sn-H insertion reactions, the [1+2] addition to isoprene and t-butylacetylene, and halogen atom abstraction from carbon tetrachloride.</p> <p> Absolute rate constants for quenching of 29 with the above mentioned scavengers were obtained by direct measurement of the germylene decay kinetics, over the concentration range where the formation of the digermene was more than 70% quenched. This ensures that the decay of 29 was dominated by the reaction with the trapping reagent.</p> <p> Absolute rate constants for reaction of the same reagents with 30 have also been determined for most of the scavengers studied. However, the digermene was found to be considerably less reactive than phenylmethylgermylene in all cases.</p> <p> The trends in spectroscopic properties and reactivity of simple germylenes in solution are discussed.</p> / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/21429 |
| Date | 01 1900 |
| Creators | Dumbrava, Ileana Daniela |
| Contributors | Leigh, William J., Chemistry |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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