Satoshi, You are of course correct, and 14f is the lanthanoid contribution, not 4f32, which was an incorrect juxtaposition of total shell and f-shell. To make this clear, I have expanded the shell to show all the shells and not abbreviation to eg [Xe].

]]>Thank you very much for your extensive explanation and calculation. I have a foolish question. What does 4f32 mean? I thought 4f orbital only takes up to 14 electrons…

It seems like we can not simply count valence electrons like organometallic chemists do for the d-block complexes (18-electron rule). Is it because electrons in f orbitals behave differently？ For example, I read 4f orbital is too compact to be considered for valence electron counts. I have no idea if it is true. (https://pubs.rsc.org/en/content/articlelanding/2012/sc/c2sc20448g)

Is there a simple way to say if a complex fulfills 32-electron criteria or not?

]]>[Xe].4f14.5d1.6s2 which when ionised to the 3+ system becomes formally

[Xe].4f14. or in full

**1s2.2s2.2p6.3s2.3p6.3d10.4s2.4p6.4d10.5s2.5p6.**14f.5d0.6s0. (where 14f is added by the lanthanoids and [Xe] is shown in bold).

Summing the shells gives: 2.8.18.32.8.

Adding three Cp^{–} units adds 18 electrons to the valence shell, hence yes formally

[Xe].4f14.5d10.6s2.6p6 or again in full

**1s2.2s2.2p6.3s2.3p6.3d10.4s2.4p6.4d10.5s2.5p6.**14f.5d10.6s2.6p6

and shells sum: 2.8.18.32.18.8

I note that Lu(Cp^{*})_{3} is a known crystal structure (DOI: https://doi.org/10.1021/om050709k) and that further coordination to this motif by thf is also known, ie https://doi.org/10.1016/S0020-1693(00)84558-2

You might also be interested in some history for the idea of a molecule of the (day, week, month, year). Arguably, it started in the early days of the WWW with the publication in 1994 of this communication DOI: https://doi.org/10.1039/C39940001907 and the follow up full article DOI: https://doi.org/10.1039/P29950000007 Wondering how to exploit some of the features described there, three chemistry departments in the UK decided to launch a molecule-of-the-month feature in late 1995. The history of the project was described some 20 years later at https://doi.org/10.3390/molecules22040549 One of the original URLs is https://www.ch.imperial.ac.uk/motm/ and the one at Bristol continues to add monthly molecules this day @ http://www.chm.bris.ac.uk/motm/motm.htm

]]>Greetings Michael. The chirality is a general form known as axial chirality, sometimes also helical chirality and relates to the sense of direction of rotation of the axis or helix. It is explained here: https://en.wikipedia.org/wiki/Axial_chirality. A lemniscate, or figure 8, is considered to have two conjoined helices, and if they both rotate clockwise (from closest to furthest from the observing axis) it is designated P,P (P= positive) or M,M ( M=minus) for anticlockwise. We showed (DOI: https://doi.org/10.1021/ja710438j) that a more general computable notation which can be used to achieve the same effect is the linking number, Lk, which can have positive or negative integer values and the value of the integer specifies the number of crossing points in the helical topology.

]]>How are the designations (M,M)- and (P,P)- defined? I thought I knew a lot about chemistry nomenclature, but I have never run into these before. Thank you in advance for your reply. ]]>

Thank you very much for the fascinating blog post regarding the 32-electron rule. Isn’t LuCp3 32 electron metalllocene complex? https://pubs.acs.org/doi/10.1021/om100240m

Thank you,

Satoshi Takebayashi

]]>https://pubs.acs.org/doi/10.1021/ja963656u ]]>

Tunnelling occurs through a potential energy barrier. If there is no barrier, then no tunnelling can occur. In this case, a free energy barrier.

]]>that was my own computations back in 2016. The idea came from high stability of [XeF8]2- dianion. I even tried to compute the lattice parameters for bcc Cs[CsF8] (space group 89) but ran out of computing resources 🙂

]]>Can you elaborate where you got your information from?

An ωB97XD/Def2-TZVPP calculation on the anion CsF_{8}^{–} gives a bond length of 2.01Å, and all positive force constants. The highest, all symmetric Cs-F mode is 493 cm^{-1}. The Cs-F Wiberg bond index is 0.446, and the total Cs bond index is 3.57. There are no significant F-F orders. The HOMO is shown below (antibonding in F-Cs region).

Accordingly, the cation CsF_{8}^{+} has a shorter Cs-F bond length of 1.916Å, a higher symmetric Cs-F stretch of 538 cm^{-1}, and larger Cs-F Wiberg indices of 0.488 and Cs total bond index of 3.91.

FAIR Data provided at DOI: 10.14469/hpc/10383

]]>The relationship is ΔG = -RT ln K. So two things there, need ΔG rather than ΔE and natural rather than base 10 logs. That should give the correct temperature dependence. The equilibrium does not involve electronic transitions. And the concentration of hydronium hydroxide is so small it would not register in any absorption spectrum.

Hope this helps.

]]>Who knows, it might exist in inter-stellar space!

]]>The form of C_{4} with Td symmetry has two electrons in a triply degenerate Td orbital and so must undergo Jahn-Teller distorsion to the lower C2v symmetry. This species is 106.0 kcal/mol higher in free energy than the bicyclic aromatic form and is a second order transition state. The first of these -ve force constants has vectors that distort back to the bicyclic form.

The second has vectors that distort to a “methylenecyclopropene” like structure (but without the hydrogens). So the answer to your question is that the tetrahedral form is not stable.

Not comprehensively investigated, but it is certainly more stable than linear C=C=C=C by ΔG 8.4 kcal/mol at the CCSD(T)/Def2-TZVPPD level (see DOI https://doi.org/10.14469/hpc/10226).

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