Talk:(Pentamethylcyclopentadienyl)aluminium(I)

Wiki Education Foundation-supported course assignment
This article was the subject of a Wiki Education Foundation-supported course assignment, between 6 September 2018 and 11 December 2018. Further details are available on the course page. Student editor(s): Brytang. Peer reviewers: Hyehwang Kim, Beccalouj.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 16:29, 17 January 2022 (UTC)

Peer review
The brief discussion on the history of (pentamethylcyclopentadienyl)aluminum(I) synthesis was nice, but it could perhaps be expanded upon further. Are there any recent examples that explore the reactivity of this compound? And if so, does it partake in any interesting chemistry?

I liked the brief discussion on the crystallographic data of Cp$^*$Al. One minor point -- the part where the author describes how the \ce{C5Me5-} is parallel to the opposite base of the \ce{Al4} tetrahedron is not cited. The same is true for the discussion on the distance between Al and the Cp$^*$ ring.

It was nice of the author of this review article to report computational studies of [Cp$^*$Al] and [Cp$^*$Al]$_4$ that had been published in the literature, such as the natural bond orbital (NBO) analysis and calculations on the HOMO-LUMO gap. However, including information on the level of theory used in these calculations could be useful.

Has the author tried to reproduce these calculations on these two aluminum complexes using GAMESS? If so, do the numbers match qualitatively with the reported values? Does the author observe a significant decrease in the HOMO-LUMO gap of the tetrameric complex compared to the monomeric complex?

It was nice to see the section on reactivity of these complexes, especially the reaction between [Cp$^*$Al]$_4$ and excess selenium and tellurium to form the heterocubane structures, and its properties as a ligand.

However, including some more examples, especially recent papers on the reactivity and formation of these aluminum complexes could serve to complete this review article. For instance, there is a 2018 paper from Braunschweig (\textit{Chem.\ Eur.\ J.} \textbf{2018}, \textit{24}, 11795-11802) that details the Lewis base-induced disproportionation of a pentamethylcyclopentadienyl substituted dialane (an Al$^{2+}$ complex) into Al$^{+}$ ([Cp$^*$Al]$_4$) and Al$^{3+}$ products. In that paper, there are also computational mechanistic studies which could be discussed in the review article as well.

There is a 2015 paper by Meng et al. (\textit{Dalton.\ Trans.} \textbf{2015}, \textit{44}, 14092-14110) where they computationally study Cp$^*$$_4$Al$_4$ and \ce{Cp4Al4} and find that the former complex is more stable due to the presence of H--H between the methyl groups on the same and different Cp$^*$ rings and not due to the Al--Al bonds. This could be something mentioned in the review article as well.

Furthermore, there is a 2009 paper by Schn\"ockel et al.\ (\textit{Chem.\ Eur.\ J.} \textbf{2009}, \textit{15}, 12180-12183) on DFT calculations on the hindered disproportionation of \ce{Cp$^*$4Al4} even at high temperatures above 100 \degree C, in contrast to the unsubstituted \ce{Cp4Al4} which spontaneously decomposes to Al$^0$ and Al$^{3+}$ above -30 \degree C. In this paper, the authors propose that formation of metalloid clusters present a barrier to the formation of metallic aluminum. Summarizing this work would be valuable to the review article, as it presents a computational explanation for an experimental observation that had not been discussed prior to this paper.

Finally, there is a 2008 paper by Arnold et al. (\textit{Chem.\ Commun.} \textbf{2008}, 4043-4045) in which the authors isolate a new aluminum complex, aluminum(II) diiododialane which was found to be a precursor to the synthesis of \ce{Cp$^*$4Al4}. Discussing this paper would also strengthen this review article.

Performing a more exhaustive search of the literature on \ce{Cp$^*$4Al4} and summarizing their results would serve to greatly improve this review. — Preceding unsigned comment added by Hyehwang Kim (talk • contribs) 01:50, 1 December 2018 (UTC)