Talk:Mod:wd812org

MARK: 49%

1.1 Part 1 (45%) - 22/45 I am missing finding a brief introduction and a small discussion about MM and the different forcefields you could have applied and why MMFF94s was your chosen one. Overall the discussions in your script are very vague, you should have tried to find more experimental data in the literature and compare them with your results, as that´s how you check normally your calculations when doing computational chemistry. Alone, the results of the calculations doesn't tell you much, with this type of calculations you predict experimental outcomes, therefore, you will always need to present experimental results when presenting results of your calculations.

1.1.1 Formation and Hydrogenation of Cyclopentadiene Dimer (10%) - 4/10

Be careful with your writing, this sentence ("Cyclopentadiene dimerises to produce the endo adn The formation of the endo and exo products were manipulated below in Figure 1") is confusing...

Figure 1. The optimization results of the cyclopentadiene dimers -> Do you mean Table 1? Be careful when naming your figures/tables, you should include an appropriate notation for the figure/table and the title.

Also, you should have included a brief introduction of what you are doing, not just a mere a recipe of what you did. I am finding this exercise very uncompleted.

Due to spelling mistakes and the lack of an introduction to this exercise, you cannot be awarded with the full mark for this exercise. However, your discussion about the control of the equilibrium and the calculated energies are corrected. Also, in the second part of this exercise you were meant to discuss the kinetic vs thermodynamic control of the reaction, as well as introduce the exercise and discuss more deeply the main differences in the energetic terms for the different molecules.

1.1.2 Atropisomerism in an Intermediate related to the Synthesis of Taxol (10%) - 3/10

Be careful with your conformations, molecule 10 is the other way around, the first one is a boat and the second a chair. I think that's why your energies are wrong, as always you would expect the chair conformation to be more stable than the boat, due to the geometry of the molecule, you should have added a discussion about this in your script. Besides that confusion, in this exercise you are meant to speak about the hyperstability of this alkenes...

"Use the MMFF94s force-field to determine the most stable isomer (9 or 10), and to rationalise why the alkene reacts slowly (hint: read the literature on hyperstable alkenes![6]. Pay particular attention to the conformations of the resulting optimised structure, to see if any aspect of these structures could be improved by further minimisations (preceeded if necessary by a manual edit of the structure to move atoms into more correct orientations)."

1.1.3 Taxol NMR - Spectroscopic Simulation using Quantum Mechanics (25%) - 15/25

You should try and write your report using a more appropriate language, i.e. what you have done is generally written in past simple. Also, you don't need to detail step by step what you did, writing an introduction of the problem you are going to address, how you are going to solve it and why, then briefly explain the method used (avoiding bullet points) and finally your results with the appropriate discussion and main conclusions.

1. 3/5 In order to be awarded with the full mark in this section, you should have compared the energy of both conformations. Also, you don´t give any energy values for this compound, how do we know that you have obtained the most stable form here?

2. 12/20 I am certain that you could have used benzene as a solvent in these calculations. Also, you could have presented the analysis of the deviation from literature values in a more visual way (i.e. plotting atoms vs the deviation of the computed values vs literature values). But you do a good analysis about the possible sources of errors and even though you could have calculated the NMR using benzene as solvent, you managed to calculate both spectra.

1.2 Part 2 (55%)- 27/55

Well done, here you introduced briefly the exercise, you should have done the same in the first part.

1.2.1 The Crystal Structures of the Shi Catalyst and the Jacobsen Catalyst (5%) -5/5 Well done finding both structures and discussing some of their most interesting features using literature research.

1.2.2 The Calculated NMR Properties of the Epoxides (5%) 2/5

A comparison with the literature is missing. This is the main part of this exercise as the calculations are very straight forwards.

1.2.3 The Assignment of the Absolute Configurations for Alkenes 2 and 4 (35%)- 16/35

Again, well done introducing the exercise, this is what should have been done in all the exercises of the first part, otherwise the report doesn´t flow.

1. Calculation of the chiroptical properties- 16/35

4/15 In this exercise comparing literature values with your calculated values is a significant part of the mark, but you don´t report any literature value. Also, the values for the OR that you obtained are very different of what is expected and other students have reported in the past. Because you don´t attach your log files or mention the energy of the systems, I don´t know what has happened with your models. Sorry, this exercise is very incomplete even though the VCD spectra look sensible.

12/20 Well done calculating the enantiomeric excess, the results are correct. However, you are supposed to compare this values with literature values too. Also your discussion and script is somehow misleading, please be careful with what you write.

NB: I could´t find this animation you mention here To get better inspection of the transition state, the .log file of the configurations possess the lowest energy values(labelled red in the above table) is opened in Gaussview 5.0 The animation simulating the transition state can be obtained by checking the Result-->Vibration-->Starting Animation in Gaussview. The animation is then saved and uploaded onto the wiki page.

1.2.4 NCI Analysis for the Transition State- 3/3 Well done with the analysis and discussion.

1.2.5 QTAIM Analysis for the First Transition State of RR Series of Shi Epoxidation- 1/3 There is no discussion here.

1.2.6 New Candidates- 0/4 This part wasn´t answered.