Talk:Mod:fs1309module 3

Cope Rearrangement

Presentation:

Data clearly tabulated. Good use of animations to show imaginary frequency for chair. Use of Jmol would have allowed visualisation of structures at different angles. Appropriate use of file sharing.

Results:

Investigated many of the anti/gauche conformers inc. gauche 3 – good. Would you expect gauche 3 to be the lowest energy conformer? Some explanation would be useful here. Included detailed analysis of difference in geometry of anti-2 isomer using HF and B3LYP methods. Note, you cannot compare energies between different methods (HF and DFT), they’re calculated on different energy scales. Frequency analysis good, including IR spectra and thermochemical data at 298K – Results for 0K?

Boat/Chair TS: Results good, TSs found. IRC calculated for chair using multiple methods – good! Could also consider boat. Activations energies calculated for both levels of theory at 298K and 0K – v.good. Where is result for B3LYP method at 298K? I think in the table ‘Summary of energies and transition structure obtained from HF/3-21G’, for the column ‘sum of electronic and ZPE’ the title should be ‘sum of electronic and thermal energies’ and for each of the literature values here you have written 234 instead of 231. Maybe this is where some of the confusion came from?

Understanding:

Good overall introduction. A more thorough conclusion would be useful. Sometimes steps taken confusing, and have to refer back to original script with instructions as student has named things ‘method b’ etc. More explanation as to why steps were taken would also help report, e.g. what is the use of IRC?

Diels Alder

Presentation:

Generally OK. Data clearly tabulated. Animations of TS would be good, as sometimes arrows hard to visualise. Again use of Jmol would be useful.

Results:

MOs for butadiene good, correct symmetry noted. MOs for ethylene?

TS – Results good with explanation of HOMO/LUMO interactions - Good use of diagrams here. Correctly noted C-C bond forming distance is < 2 x vdW radius of C, implying bond forming.

Endo/exo: Results generally good. Investigated using 2 levels of theory – good. Endo is lower in energy than exo for BOTH levels of theory according to your results; they do not have ‘opposite results’. Have explained secondary orbital overlap – but is this effect apparent in your results?

Understanding:

An introduction to the topic would be good. Steps taken mentioned, but reasoning behind these steps (e.g. use of keywords, why certain levels of theory were used etc.) was a little lacking. Very good explanation to allowed/forbidden reactions. Secondary orbital overlap explained well, but could’ve been applied to results.