Talk:Carborane acid

Structure of the acid itself

The article's subject is "Carborane acid", and the acidity of these compounds is worthy of discussion (the structure and stability of the conjugate base anion). However, nowhere is the structure of the acid itself actually discussed. In particular, where is the acidic H located? Is it bonded to a specific atom of the anion (or perhaps hopping among several sites) is it a separate ion (either externally or within the cage as an inclusion compound). None of the diagrams include it (there is a different H that is present), and the § Structure section appears to be about further reactions of the anion, despite saying it is about the acid. DMacks (talk) 07:35, 2 July 2017 (UTC)

Despite being the strongest acid

In the acidity section, it says that Carborane acid is the strongest acid, although by the H_0 values, Fluoroantimonic acid is the strongest acid (see Wikipedia article about Fluoroantimonic acid). — Preceding unsigned comment added by 2A02:8108:1BF:704E:4D1D:C50A:2BAC:953F (talk) 14:00, 4 June 2018 (UTC)

Check the first paragraph of the acidity section to see why the H0 value for carborane acids cannot be measured. Conversely, the pKa of fluoroantimonic acid is not well defined.Alsosaid1987 (talk) 17:50, 29 November 2018 (UTC)

Another Stronger Acid?

What about the pK_a of H(CB₁₁(CF₃)₁₂) Anoop Manakkalath (talk) 08:24, 29 November 2018 (UTC)

AFAIK, that particular acid has only been investigated in silico, and it is quite acidic according to the calculated gas phase acidity. However, its anion has never been protonated and isolated as the free acid. For reasons I don't see right away, the authors state that this carborane anion is explosive (despite its "inertness"), which limits investigations. Alsosaid1987 (talk) 17:50, 29 November 2018 (UTC)

Any studies on Silicon and Germanium analogues of Carborane acids? (Eg. H(SiB₁₁F₁₂), H(GeB₁₁F₁₂) etc.) Anoop Manakkalath (talk) 05:46, 18 October 2019 (UTC)

I don't know about the Si or Ge analogues, but I would guess that the weaker bond strength and mismatched bond length would be detrimental to its stability.

I am aware that the CF3 substituted one is expected to be even stronger in the gas phase (by quite a bit, I think, it might be less than 200 kcal/mol, makes sense due to the larger available space for charge spreading). However, I also remember reading that work on these have stopped after workers (unexpectedly) found that one of these compounds detonated. (If you think about it, the 140 kcal/mol BF bond is a lot better than the 110 kcal/mol CF bond, so given some obscure - probably radical-based - initiation process, all those CF's are going to break to make a bunch of BF3 or BF4-!!) Alsosaid1987 (talk) 03:19, 19 October 2019 (UTC)