Talk:Mod:wyc08mod3

Grade: B

Cope Rearrangement: Presentation: Good use of Jmol. Animations would be useful to view vibrations. Data clearly tabulated. Files shared when appropriate. Results: Reactants - Investigated anti and gauche isomers inc. gauche 3. Correctly noted this as lowest energy isomer and reasoned why using MO orbitals. Re-optimisation of anti 2 - Can’t actually compare energies from different levels of theory, they’re calculated on different energy scales! Geometry differences analysed and good comparison to literature. Frequency analysis inc. IR spectra and thermochemical data good. Considered energies at both 298K and 0K. Stated ‘It can be seen that as temperature decreases, the stability of the conformer increases (compare -234.612a.u. at 298.15K to -234.611a.u. at 0K)’ – where does this data for 0K come from? Chair/Boat TS: Results good. IRC present and showed reached a minimum - good. Activation energies calculated for both levels of theory for 0K and 298K. Understanding: Generally good. Good introduction. Steps taken clear and some reasoning given. Could build upon this explaining use of keywords e.g. opt=noeigen etc. Summary a little brief. References to primary literature good.

Diels Alder Presentation: Slightly strange layout. However, good use of Jmol –something wrong with Fig 17. Data tabulated. Legends given to all figures/tables. No use of files sharing – would be useful at times. Results: MOs of reactants and TS good. Good understanding of interactions of MOs of reactants. For TS, results good - correctly note C-C distance for bond forming is < 2 x VdW radius therefore shows shared electron density and bond is in process of forming. Imaginary frequency of TS given, animation or visualisation of this would be useful. Exo/endo TS: Symmetries good. Endo is lower in energy. However can’t read some of reasoning as is hidden by other text. Stated ‘such an interaction, however, does not occur in the endo state’ referring to secondary orbital overlap for the endo state, however this is where it is thought it IS apparent. Understanding: Good concise introduction. Interaction of reactants’ MOs and allowed/forbidden reactions explained. Secondary orbital overlap could be explained in greater detail, although correctly noted in your MOs this effect isn’t apparent. Reference to primary literature. Lack of summary/conclusion.