Comments

Cyclopentadiene 110% (0.20)

Nice use of the chart to visualise the difference in product energies!

"mono-hydrogenated"

I know what you mean, but be careful there with your choice of words.

Actually you'd describe the first hydrogenation as a di-hydrogenation because you reduce the compound by adding two hydrogen atoms. Try to use a more precise language. :) (That's just nitpicking, though...)

Excellent section!

Nice excursion on the transition states there!

Good work on the ghost atoms. I learnt something new from that as well!

Taxol (0.25) 100%

Good section!

I know that the wiki doesn't support proper formatting of images. Still, please don't put images into tables, that's generally not beneficial for the layout, either. If you want them to be out of the way, just provide a link. In papers NMR spectra are generally put into the Supporting Information.

"A further calculation was done locally using the same basis set, but with a LanL2DZ pseudo-potential for both sulphur atoms. " Okay, I'm not very well versed in this particular are, but I'll try my best. Take it with a grain of salt though.

The LanL2DZ is actually a core potential, which means you approximate the core orbitals. The core orbitals should already be well representend by the B3LYP/6-31G approach since they are not very diffuse. The valence orbitals would then be represented by the 6-31G basis set. I'm happy for you to prove me wrong here!

I don't know how the heavy atom effect actually works, but I'm working under the following assumption. If the core orbitals are responsible for the heavy atom effect, then approximation of the core potential might not be very helpful because it would not be likely to be much more precise than the 6-31G. In that case, neither method would be really useful to describe the sulphur.

If the valence orbitals are responsible for the effect the LANL2DZ (and again it is only my educated guess and I might be completely wrong!) won't help much and I'd go for a method with more precise description of the orbitals. Either 6-311Gdp, maybe also throwing in an Gdpf for any empty sulphur d-orbitals that might be interacting with the occupied orbitals) or going for a cc-pVTZ ("valence triple zeta" ~= 6-311G) basis set or something higher - do have a look at the Dunning basis sets on the Gaussian help pages. From what I have read they might be more precise than the 6-31G family - just not as commonly used.

Just curious: Have you ever done a google search on "DFT sulphur heavy atom effect"? Someone is bound to have run into this problem before. If not Henry Rzepa would probably recommend you to write a paper about it. ;)

"allylic proton"

Surely, that would be a "vinylic proton", no? Careful there!

The difference for the aromatic proton is more likely to be due to conformational effects. The olefinic position is more sensitive to changes in its environment. Probably the conformation in solution is a different one from the one you calculated in gas phase. The basis set is generally good enough to describe olefinic/aromatic protons - or we could throw DFT into the bin altogether.

If not completely correct, it's still a very good discussion on the olefin proton! Spotting such a deviation and discussing it to the best of your knowledge is what research is mainly about.

Epoxide (0.05) 98%

"However the enantiomeric excess decreased from 92% to 86% and favoured the other enantiomer. " So, you mean that, for example, instead of (R) it's (S)?

This is really important info and you should stress this much more. The way you say it sounds like: "There's a decrease in ee... and yeah, well, the enatiomer changes as well, but nevermind"

You put in thought and effort to find this information. Your discussion should reflect that, so just try to sell it a bit better.

NMR 100% (0.05)

Very nice!

Optical Rotation and TS 90% (0.35)

"a further optimization " => "a further geometry optimizsation" Also, avoid brackets in scientific texts and try to reflect the order of how you did it by saying sth. along the lines of: "The geometry was optimised (which method?) prior to calculating the OR. The OR was then determined using the DFT B3LYP/6-311++G(2df,p) method ..."

"thus increasing the realism of the calculation" That's lab jargon. You're increasing the accuracy of the calculation.

"The trans-methylstyrene oxide shows a deviation from literature of approximately 10o. This is a reasonable correspondence since there is a relatively large deviation in the literature, mostly likely due to errors in concentrations and temperatures recorded. At first inspection, the 1,2-dihydronapthalene oxide rotation value appears to deviate massively compared to that of literature, however this may not the case. As this is a measured angle, one can add or subtract 180o to each value, due to the reference point that was being used. There is numerous values in literature that show a 180o difference with that of other literature values. Thus subtracting 180o from 36.45o yields -143.55o which is in good correspondence to the cited value of -144.9o. In general one can quote an optical rotation whose value is greater than |100o| with more confidence than one with an absolute value of less than 100o. "

Yes, you're right! However, the difference between -39° and -144° is 105°, which hints at an inconsistency between the literature values. So, you still don't know if the data is correct and you need to put this in your report.

There's many more data points for the dihydronapthalene (scan reaxys for optical rotation) between ~+0° and +45°. While the (additional) data looks reliable you'd need to consider the reliability of the method below 100°. You mention that later but it would have been good to discuss it in more detail for this molecule.

"There is a vast trove of literature values available so determining the absolute configuration is a relatively easy feat, but the accuracy leaves something to be desired." So, it's relatively complicated, is that what you're saying? ;)

"The synthetic procedure of an optical rotation is relatively easy" You wouldn't say it like that. Use something like "The experimental determination..."

Good discussion on the enantiomeric excess of the Shi catalyst.

QTAIM and NCI 110% (0.10)

Excellent!

Final notes

Very good report!