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Why are all types of compounds of boron monomers with the exception of diboranes and other boron hydrides? Can you explain why structure of diborane is unusual? example: BCl3, BI3 are monomers of trivalent boron; whereas B2H6 or (BH3)2 is a dimer having unusual structure.
In BCl3 and BI3, there is donation of electron density from the filled p-orbitals on the halides to the vacant p-orbital on boron, stabilising the boron monomer. With hydrogen, no such donation is possible as it has only one electron and no occupied p-orbitals. I will eventually add this (and other information) to the article, after I have finished adding to Borane--Amigadave 11:45, 2005 Apr 26 (UTC)
Also, if you think that B2H6 is strange, Al2Me6 is analogous, with two bridging methyl groups (five coordinate carbon).Smokefoot 14:00, 31 January 2006 (UTC)
- please give the preparation of B2H6 - how is it manufactured?
We could really use a picture of the borane dimer. DS 16:44, 19 September 2005 (UTC)
Is this Aluminium Hydride? If so it should link to that article.Dajwilkinson 23:53, 15 May 2007 (UTC)
H. Christopher Longuet-Higgins
I have added the name of the undergraduate student. H. Christopher Longuet-Higgins went on to great things as a theoretical chemist and was a member of the International Academy of Quantum Molecular Science. He then changed fields completely to Artificial Intelligence. I will write on article on him sometime but the two fields make it difficult. I'm working through the redlinks on International Academy of Quantum Molecular Science. Of course, if anyone else wants to write it, please go right ahead. --Bduke 00:58, 19 June 2006 (UTC)
It's 4 flammable/ 4 toxic/ 3 corrosive, not 3 toxic.
I had access to a link to this at one time, but I've lost it.
- I corrected this to 4/4/4/W (and added a link) as this is the value from the International Chemical Safety Card from NIOSH. Interesting, given the rarity of a '4' in all categories. --ScanningElectronMike (talk) 22:28, 14 August 2015 (UTC)
Contradiction in Terms
- So sweet it's unpleasant?
- Saccharine? —Preceding unsigned comment added by 126.96.36.199 (talk) 13:52, 8 June 2010 (UTC)
- A paradoxical combination of fragrant and unpleasant odors? Like partially-rotted fruits, perhaps?—Tetracube (talk) 23:18, 8 June 2010 (UTC)
Dialane exists and is known
Of the other elements in Group 13, only gallium is known to form a similar compound, digallane, Ga2H6. Aluminium forms a polymeric hydride. No hydrides of indium and thallium have yet been found.
My english is too bad and I don't take the risk to dirty the article, however I want to signal that dialane (Al2H6) exists and is known. See . Kiss kiss, bye bye. —Preceding unsigned comment added by 188.8.131.52 (talk) 16:05, 24 January 2009 (UTC)
- You are quite correct, the existence of Al2H6 is even mentioned (and referenced) in the article Aluminium hydride.
- However, polymeric AlH3 is far more common and stable than Al2H6.
Bonds in Diborane
I removed the following dubious sentence from the section "Structure and bonding":
- The structure is isoelectronic with C2H62+, which would arise from the diprotonation of the planar molecule ethene.
First of all, the formula for ethene is C2H4, and deprotonation means removal of hydrogen, which would result in an anion, not a cation, as well as having less than 4 hydrogens. That is to say, either C2H3-, or C2H22-. This is completely inconsistent with the claimed cationic formula C2H62+. Going the other way, protonating ethene would give either C2H5+ or C2H62+. The latter matches the formula claimed, however, I have never heard of protonation involving the insertion of a hydrogen into a
covalent sigma bond between two carbon atoms. Even if the unstable species C2H5+ could be further protonated, I highly doubt it would result in something isoelectronic with diborane.
The only way I can see a carbon equivalent of diborane forming is via the dimerisation of the carbocation CH3+, which is unfortunately an extremely unstable carbocation that is very unlikely to exist long enough to dimerise with another instance of itself.—Tetracube (talk) 22:29, 9 March 2009 (UTC)
- You misread and then misconcluded, but we are all reading too fast these days, so no big deal. The item you find objectionable said diprotonation, not deprotonation. And C2H62+ would be isoelectronic with diborane. The question is whether this dication would be isostructural. Deprotonation does not mean removal of hydrogen, the term refers to removal of protons.--Smokefoot (talk) 23:07, 9 March 2009 (UTC)
- Mea culpa. So it did mean protonation (and on that note, I meant "removal of H+", which is equivalent to removing a proton, when I referred to deprotonation. Talk about reading/writing too fast. :-)). I still think it's a dubious claim, though. Would protonating C2H5+ break the C-C sigma bond, as would be necessary for the resulting dication to be isoelectric with diborane? I highly doubt it.—Tetracube (talk) 23:28, 9 March 2009 (UTC)
I searched the literature for the ethane dication, [C2H6]2+, and found a paper (G. Rasul, G. K. S. Prakash, G. A. Olah, J. Phys. Chem. A, 2005, 109 (5), pp 798–801) that answers most of the questions posed here:
- "Neutral diborane, B2H6, is isoelectronic with the C2H62+ dication."
- "the 2e-3c bonded carbonium-carbenium structure 1 is more stable than the doubly hydrogen bridged diborane-type structure 2 by 12.4 kcal/mol."
- however, for the silicon analogue [Si2H6]2+, "the 2e-3c bonded siliconium-silicenium structure 8 is 8.7 kcal/mol less stable than doubly hydrogen bridged structure 9."
- OK, maybe I'm still stuck in the old-school mindset... I was thinking of the mechanism of adding a proton to the species C2H5+, which I assume has a sigma bond between the two carbon atoms. The only way to get something isoelectronic with diborane with this process is if the new proton gets inserted between the carbon atoms. But what do I know, maybe from the MO perspective all of this is just trappings from an obsolete theory that has no real basis in reality.—Tetracube (talk) 17:12, 10 March 2009 (UTC)
Diborane is a electron efficient molecule.in this molecule boron undergoes sp3 hybridization. in this molecule to form ethane like structure boron gives fore electrons.and each hydrogen give one electron.12 electrons are obtained. so they can form only 6 covalent bonds only.to ehane like structure 14 electrons are required. —Preceding unsigned comment added by 184.108.40.206 (talk) 08:51, 11 April 2010 (UTC)
Bond angles and bond lengths
The only reference I can find has different B-H bond lengths from the ones in our pretty picture. Has anyone got a reference for the bond lengths we use? Axiosaurus (talk) 12:12, 28 September 2013 (UTC)
- Consensus is emerging at Wikipedia talk:WikiProject Chemistry to revert and rethink the borane articles. At least that is my guess because we dont want the readership being tricked into thinking that BH3 is a major reagent or actor in much chemistry, so it would be discussed within a great context. But that is only my guess the way this article development would go. The B-H distance of the monomer is however useful. In general I think that we need a structural report for as articles on chemical compounds.--Smokefoot (talk) 14:42, 28 September 2013 (UTC)
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