Talk:Gallane

Weird properties

Some of the stated properties for this compound don't seem right at all. How is it acidic? It appears to react like a hydride in that it reacts with water to give H₂, it's certainly not an Arrhenius-acid as it doesn't generate extra H
₃O⁺
. If it reacts with H₂O can it really be described as being hydrophobic? Project Osprey (talk) 21:51, 23 September 2013 (UTC)

As per the Acid–base reaction#Arrhenius definition section,

"Overall, to qualify as an Arrhenius acid, upon the introduction to water, the chemical must either cause, directly or otherwise:

• an increase in the aqueous oxonium concentration, or
• a decrease in the aqueous hydroxide concentration."

I draw your attention to the second note. This is not to say that gallane cannot act a base, just that it is more prone to act as an acid. Would you that I amend the relevant section to mention its amphotericity, or would you rather have it focus on its primary behaviour?

Whether something reacts with water or not, does not determine whether it is hydrophilic or hydrophobic. Gallane is hydrophobic because of its zero dipole moment. Plasmic Physics (talk) 22:05, 23 September 2013 (UTC)

I took the initiative concerning amphoreticity. Plasmic Physics (talk) 23:07, 23 September 2013 (UTC)

Amphotericity does seem better. I just think its odd to discuss the hydrophilicity of something that's incompatible with water, it rather implies that it hydrolyses slowly enough for that behaviour to be observed. If that's true then fair enough, but the article gives the impression that its far more unstable than that. (what is it with you and weird hydrides! ^.^ ) Project Osprey (talk) 23:16, 23 September 2013 (UTC)

It just occured to me that the reaction of gallane with base is

GaH₃ + OH^- -> H^- + H₂GaOH

H^- + H₂O -> H₂ +OH^-

no net consumption of OH^-

Similarly with acid (just taking the first hydride as an example) also involves no net consumption of H⁺

GaH₃ + H⁺ -> H₂ +GaH₂⁺

GaH₂⁺ + H₂O -> GaH₂OH + H⁺

Isn't this simply hydrolysis - no neutralisation of acid or base so no "amphotericity"- just "catalysis" by acid (as observed), or base if this mechanism is correct.

Axiosaurus (talk) 17:46, 17 October 2013 (UTC)

You're assuming that they are aqueous reactions. No water = no regeneration of the hydroxide/proton. Plasmic Physics (talk) 23:02, 17 October 2013 (UTC)

Arrhenius - is all about acids and bases in water. But if the solvent isn't water - well what is it?? Axiosaurus (talk) 07:03, 18 October 2013 (UTC)

(Just a side note:I didn't explicitly say that gallane is an Arrhenius acid/base, only that it has character corresponding to an Arrhenius acid/base.) The solvent could be anything so long as it doesn't interfere with the posited acid-base reactions. Moreover, what happens with the reaction products is a moot point, is it not - as it does not change the nature of the reactions? As a metaphor, if a dropped ball bounces, and is then caught, it does not change the fact it bounced. Even if it was allowed to roll away instead of being caught, the ball still bounced. Plasmic Physics (talk) 22:34, 18 October 2013 (UTC)

I imagine a viable reaction could be: gallane with benzyltrimethylammonium hydroxide under THF. Plasmic Physics (talk) 22:41, 18 October 2013 (UTC)

Hydrolysis may occur by these routes, but it is overshadowed by the simple hydration reaction, due to the weak dissociation of water. Plasmic Physics (talk) 22:48, 18 October 2013 (UTC)

I'm sorry but I'm just a simple chemist at heart. Arrhenius acids and bases always refer to systems where water is the solvent. Amphoteric means reacts with acids and bases, capable of reacting with acid or base and effectivelly neutralising them. This doesn't happen here. You are picking on steps in a hypothetical reaction mechanism. Also Lewis amphotericity is strange in theis context- Lewis acids accept electron pairs Lewis bases donate them, just look up the definition in the gold book. GaH3 is a Lewis acid it is NOT a Lewis base.Axiosaurus (talk) 07:10, 19 October 2013 (UTC)

GaH3 , molecular monomeric form

It may be worth mentioning that GaH₃ has actually been observed as a transient gas phase species. (1965 paper or read Downs books on Al, Ga, In etc) so it isn't mythical. It would also be useful to add that the stable form is Ga₂H₆. It might also be interesting to note that there is no experimental evidence for monomeric GaH₃ gas reacting with water or anything else for that matter.Axiosaurus (talk) 08:48, 26 September 2013 (UTC)

Aye, but it never mentions that the gallane reacting with water, is in the gaseous state. As for its observation as a gas phase species, I thought that would be self-evident from the lede, but I guess it could always use a reference. Plasmic Physics (talk) 09:22, 26 September 2013 (UTC)

Aye, Aye. If you mean hydrolysis of a gallane adduct or oligomer then shouldn't that be made clear? And "self evident" ? Hmm! A reference would be nice. There is also the implication that monomeric GaH₃ dissolves in tetramethylethylenediamine to form a complex- firstly a reference would be good, you obviously have one, and you will be able to say from that whether it and is it really monomeric GaH₃ that reacts or digallane(6) or something else.Axiosaurus (talk) 10:15, 26 September 2013 (UTC)

I'm talking about the implied reactive intermediate, hydration adduct [GaH
₃(OH
₂)]. Yes, the tetramethylethylenediamine adduct is complex of two separate gallane units that are bridged. Plasmic Physics (talk) 11:40, 26 September 2013 (UTC)

The hydration adduct can be formed by introducing water to another adduct, causing a displacement. Or, it can be theoretically formed by attempting to generate gallane in aqueous conditions. I'll need the full reference if I'm going to add it to the lede. Plasmic Physics (talk) 11:53, 26 September 2013 (UTC)

I have rewritten the lede with references and added a section.Axiosaurus (talk) 09:38, 27 September 2013 (UTC)

Chemical properties

I have revised this section- added referenced material and flagged material. The section amphotericity could be correct - but it needs a reference. I have looked. In solute properties the statement "Gaseous gallane is a hydrophobic (non-polar) aprotic solute." just doesn't make sense- for instance the next statement says it dissolves in a polar solvent. What form of GaH₃ does this refer to? A reference is required to back this up.

The reference used to support the solution of GaH₃ in TMEDA to form an adduct is not the correct one, the 1991 paper quoted clearly states that the adduct is made by ligand displacement using the 1:1 trimethylamine adduct as a precursor. I could not find another reference to the synthesis.

I believe that a lot more work is required - but I shall await comment before putting any more effort in. Axiosaurus (talk) 13:49, 27 September 2013 (UTC)

Concerning 'solute properties', which needs to be sourced, that gallane is hydrophilic, is non-polar, or is aprotic? Gallane may not have a permanent dipole, but it does have an instantaneous dipole. It is this instantaneous dipole, which causes it to have increased solubility in polar solvents.

What form of carbonic acid is referred to when speaking about its solubility? The answer does not matter, gallane is gallane whether gas or liquid, if such a state existed. Plasmic Physics (talk) 00:56, 28 September 2013 (UTC)

Gallane is gallane- well no I disagree. Dimers and monomers reactivity wise can behave differently, consider borane, reaction mechanisms invoke the almost mythical BH₃ rather than the dimer, as they like the empty p orbital. As for solubility, experimental evidence is what we need, but I am very mindful of the experimental constraints placed on researchers, e.g access to the compound, thermal instability, ultra-dry solvents etc so I am not optimistic.Axiosaurus (talk) 08:40, 28 September 2013 (UTC)

I fixed the mistake regarding the TMEDA adduct, it was meant to be a '1', not a '2'. The statement does not imply synthesis, but solubility. Plasmic Physics (talk) 01:08, 28 September 2013 (UTC)

I am an old school chemist- facts have to be referenceable- well informed speculation isn't unless made by a very authoritative source (in this case Prof A.J. Downs (http://research.chem.ox.ac.uk/tony-downs.aspx theres a pretty picture of an MOCVD process involving a gallane adduct!) would be acceptable, you and me- definitely not!) and then weasle words like "XXX suggests" can be quoted. Have you found any referenceable solubility information re digallane(6) or the polymeric form? The reference quoted for the TMEDA adduct describes production via a ligand replacement reaction of the trimethylamine adduct not the reaction of any form of gallane with TMEDA.Axiosaurus (talk) 08:40, 28 September 2013 (UTC)

The statement in question isn't implying a reaction. Plasmic Physics (talk) 08:52, 28 September 2013 (UTC)

You're reading too much into statements, instead of taking it at face value. Plasmic Physics (talk) 09:02, 28 September 2013 (UTC)

Sorry but we disagree. Face value? - as we say in the old country "beauty is in the eye of the beholder", so for me the statement is an ugly unreferenced speculation.Axiosaurus (talk) 11:26, 28 September 2013 (UTC)

The article clearly speaks about a solution of borane in a combination of ether and the adductor. So, I don't really know what the problem is. Plasmic Physics (talk) 11:41, 28 September 2013 (UTC)

Perhaps thats the problem- you're reading a borane article! the one I am referring to is Attwood Bott el Al 1991, Inorg.Chem, p3792-3 which describes the synthesis of the gallane TMEDA adduct by a reaction of the gallane trimethylamine adduct in Et₂O, basically, add TMEDA solution to gallane adduct solution slowly, wait a while, get rid of ether, recrystallise, jobs a good'un as we say in the old country. Did some similar myself once with low valent indium/gallium compounds, but never got a paper out of it sadly, my gunk never recrystallised. Axiosaurus (talk) 17:49, 28 September 2013 (UTC)

I'm referring to the same article as you are. My point is that at some in the reaction, borane exists in a solution containing TMEDA as a major component, how it got there is not what the statement is concerned about. Plasmic Physics (talk) 22:47, 28 September 2013 (UTC)

You are confusing me, I have no idea what you are trying to say the only mention of borane is the lede that says gallaborane has been made (1989) Downs again.Axiosaurus (talk) 12:57, 29 September 2013 (UTC)

"Treatment of H
₃GaNMe
₃ with excess TMEDA in diethyl ether gave a 1:1 gallane/TMEDA adduct, H
₃Ga(TMEDA), as a white solid, which rapidly lost equiv of Lewis base in vacuo (weight loss), via a colorless oil, affording solid [{H
₃Ga}
₂{(NMe
₂CH
₂)
₂)] (1) in high yield. ...In contrast, the 1:l adduct is stable for days at room temperature in solution and in the solid." Plasmic Physics (talk) 21:26, 29 September 2013 (UTC)

True. So what? The statement in the gallane article concerns the solubility of gallane so what what you are trying to imply from this paper "if we had some gallane and we put in TMEDA it could be stable". Axiosaurus (talk) 05:41, 30 September 2013 (UTC)

I'm not implying anything, although that is more or less correct. The researchers had some gallane (as an TMA adduct), they put it into a mixture containing TMEDA, and the resulting TMEDA adduct was stable in solution. Plasmic Physics (talk) 07:00, 30 September 2013 (UTC)

Adduct formation

To me the following reaction equation is not balanced:

Ga₂H₆ + 2 NMe₃ → (NMe₃)₂·GaH₃ (-95°C)

A gallium atom and three hydrogens evaporate into nothing. To me the "2" placed after the trimeythyl amine should be in front of it, giving two adducts and no loss of atoms. As I don have any acces to literature, I am not able to correct the equation in any way. Is some else able to?T.vanschaik (talk) 18:34, 1 January 2024 (UTC)