Question about three-center-two-electron bond

[JMBuilder]

I've only ever heard of three-center-two-electron bonds with hydrogen atoms. Is it possible for something other than hydrogen to form this type of bond?

Example: Diborane forms a 3C2E bridge between the two boron atoms using hydrogen. Could something other than hydrogen be used for that bridge?

Edited August 11, 2015 by JMBuilder

[QuesoExplosivo]

Yes. Diborane, for example. Also, carbocations often have them, most famously this one: https://en.wikipedia.org/wiki/2-Norbornyl_cation

[lajoswinkler]

JMBuilder, are you perhaps implying that there could be something else out there that's "faking" the trihydrogen cation signature? Cause that would be impossible.

[Woksaus]

Yes. Diborane, for example. Also, carbocations often have them, most famously this one: https://en.wikipedia.org/wiki/2-Norbornyl_cation

Uh, aren't the hydrogen atoms responsible for the 3c-2e bond in diborane?

Some organometallic compounds contain 3c2e bonds: http://pubs.rsc.org/en/Content/ArticleLanding/2012/CC/c2cc35304k#!divAbstract

[JMBuilder]

Yes. Diborane, for example. Also, carbocations often have them, most famously this one: https://en.wikipedia.org/wiki/2-Norbornyl_cation

Diborane still uses hydrogen for the 3C2E bond. I am thinking of boron molecules, but I'm wondering if boron molecules can use something other than hydrogen for the 3C2E bond.

JMBuilder, are you perhaps implying that there could be something else out there that's "faking" the trihydrogen cation signature? Cause that would be impossible.

The what?

Edited August 11, 2015 by JMBuilder

[lajoswinkler]

Nothing, just speculating.

[QuesoExplosivo]

The 2-norbornyl cation has carbon atoms in the three-center two-electron bond, and no hydrogen atoms. Does that fit what you're thinking of?

[JMBuilder]

The 2-norbornyl cation has carbon atoms in the three-center two-electron bond, and no hydrogen atoms. Does that fit what you're thinking of?

So none of the atoms involved in the bond are hydrogen? It's just four carbons?

[QuesoExplosivo]

Three carbons in the bond ("three-center"), but yes, no hydrogens.

[JMBuilder]

I'm confused... The diborane molecule contains a 3C2E bond, but there are four atoms involved, two borons and two hydrogens, yet it still counts as a 3-center bond.

EDIT: Derp. Nevermind. Diborane has two 3C2E bonds.

Edited August 13, 2015 by JMBuilder

[Woksaus]

I'm confused... The diborane molecule contains a 3C2E bond, but there are four atoms involved, two borons and two hydrogens, yet it still counts as a 3-center bond.

The molecule contains two 3C2E bonds: the two B-H-B bonds present.

[JMBuilder]

I figured that out almost as soon as you posted. I hads a derp.

[JMBuilder]

Wait... Now the diborane molecule makes no sense to me. Boron can normally only form three bonds, yet it forms two 3C2E bonds and two normal bonds. That's four, isn't it?

[QuesoExplosivo]

And hydrogen can normally only form one bond. 3C2E bonds aren't normal.