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Author Topic: Halogen allotropes  (Read 11493 times)

Offline Supercryptid

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Halogen allotropes
« on: 01/02/2004 05:36:06 »
I've been wondering about the possibility of halogen allotropes. Usually, halogens only form 1 bond to another atom. This gives us F2, Cl2, Br2 and I2.

However, chlorine, bromine and iodine have d-orbitals that can accomadate extra electron pairs, giving them the ability to form 3 or 5 bonds to other atoms. This allows molecules like ClF3 and ClF5 to exist. But what if these extra bonds could be used to form new allotropes of halogens?

For example, what if 1 chlorine atom was in the dsp3 hybridization state and used its 3 half-filled sp-orbitals to bond with 3 other chlorine atoms? This would yield Cl4, a T-shaped molecule analogous in structure to ClF3.

Chlorine atoms can also achieve the d2sp3 hybridization state. This allows them to form ClF5, but what if those fluorine atoms were replaced with chlorine atoms, yiedling Cl6?

Well, chlorine atoms are larger than fluorine atoms, so there might be a lot of crowding in a Cl4 or Cl6 molecule, rendering it unstable. Would this crowding be enough to destabilize the molecule?

If these molecules are stable, then the following allotropes might be synthesizable: Cl4, Cl6, Br4, Br6, I4 and I6. What do you think? Might we be able to create these allotropes?


 

Offline Ylide

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Re: Halogen allotropes
« Reply #1 on: 01/02/2004 08:30:55 »
The high electronegativity and small size of Fluorine allow it to form molecules that ordinarily would not be stable if another halogen were used.  Fluorine has its own branch of chemistry...there are people that study nothing but weird fluorine behavior.  

I'm not entirely convinced it's a crowding issue, because of the existance of molecules like antimony pentachloride (SbF5) that exist in sp3d2 hybridization.  I'm thinking it has something to do with the electronegativity of fluorine or possibly an excess of antibonding orbitals in all those Cl-Cl bonds.  (remember, a bond order of zero is an unstable molecule)




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Offline lysdexia

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Re: Halogen allotropes
« Reply #2 on: 27/11/2004 03:50:18 »
*POST DELETED*

Unecessary grammatical flamebait deleted.  This is neither the time nor place for a spelling discussion.  You don't correct our spelling and we won't come to literature boards and yell at you for calling water an atom.

« Last Edit: 01/12/2004 08:43:37 by Ylide »
 

Offline chris

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Re: Halogen allotropes
« Reply #3 on: 28/11/2004 23:13:02 »
I grant you there is a spelling error in the word existence, but the it's is quiet correct. In the context above "it's" is used as "it is" and hence an apostrophe is quite correct. Unless you have spotted another one of course.

But, to be honest, I think you may have missed the point of this forum a bit. It's not (there's another it's for you) intended to teach people English grammar but to instil a healthy interest in science. Spelling can come later. I'm just very grateful to people like Ylide and supercryptid for their time and effort spent contributing to this forum and, as such, enriching the experience for everyone else.

It is very easy to criticise, but it's much harder to write the answers to some of these questions.

Chris

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Offline lysdexia

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Re: Halogen allotropes
« Reply #4 on: 17/12/2004 00:44:34 »
And Ylide misspelled unnecessary.  No, the first instance of "it's" isn't.  I'm baffled by how often people claim that I miscorrected them, that the "it's" actually meant "it is".  I'm not the blind one here.  And, no, that was not a flamebait; it was the truth.  Why do you let people be wrong?
 

Offline chris

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Re: Halogen allotropes
« Reply #5 on: 18/12/2004 11:06:34 »
Thank you, lysdexia, for your laudable attention to detail.

But with only about 700,000 thousand words on this website, I hope you don't run out of mistakes to find too quickly.

However, please do be sure to let us know about any other minor errors you spot, including typos, misplaced commas, misuse of affect and effect (I've definitely seen one of those somewhere), and the crime of crimes - split infinitives.

I think someone with a fastidious eye such as your's could make a very valuable contribution to our quality control. It would be great to have you work with us. Please do bear the offer in mind.

Best wishes

Chris

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Offline Supercryptid

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Re: Halogen allotropes
« Reply #6 on: 19/12/2004 06:49:47 »
I don't see why there would be any problems with antibonding orbitals in a molecule such as Cl4 if ClF3 doesn't have any such problems. The valence shells of all the halogens are identical, the only difference being the kernel electron shells between the atoms. In its ground state, a chlorine atom has 1 unpaired electron, the same as a fluorine atom, which I would expect to mean that the bond orders in Cl4 should all be 1.0, which means stables bond. Correct me if I am missing something (I don't do much study of antibonding orbitals).

Cl4 might also be more stable than the two Cl2 molecules that it would be formed from, since Cl4 would contain 3 Cl-Cl bonds, whereas only 2 Cl-Cl bonds would exist for the 2 Cl2 molecules. Of course, the bonds of Cl4 would probably be weaker than those present in Cl2, because of the crowding once again.

Might Cl4 and these other halogen allotropes be formed by squeezing them under immense pressure? This allows other elements to change into other allotropic forms (graphite into diamond, dinitrogen into "nitrogen diamond"), so might this work for halogens as well?
 

Offline Ylide

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Re: Halogen allotropes
« Reply #7 on: 19/12/2004 09:49:57 »
quote:
Originally posted by lysdexia

And Ylide misspelled unnecessary.  No, the first instance of "it's" isn't.  I'm baffled by how often people claim that I miscorrected them, that the "it's" actually meant "it is".  I'm not the blind one here.  And, no, that was not a flamebait; it was the truth.  Why do you let people be wrong?



If you have no valuable input to the discussion other than to criticize spelling mistakes, kindly keep your thoughts to yourself.  Some of the mistakes are grammatical and/or spelling errors and some are simply mistyped.  I don't think you're smart enough to tell the difference, so perhaps you should remain silent except to discuss the issue at hand, in this case halogen allotropes.



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Offline Ylide

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Re: Halogen allotropes
« Reply #8 on: 19/12/2004 09:50:56 »
quote:
Originally posted by chris

Thank you, lysdexia, for your laudable attention to detail.

But with only about 700,000 thousand words on this website, I hope you don't run out of mistakes to find too quickly.

However, please do be sure to let us know about any other minor errors you spot, including typos, misplaced commas, misuse of affect and effect (I've definitely seen one of those somewhere), and the crime of crimes - split infinitives.

I think someone with a fastidious eye such as your's could make a very valuable contribution to our quality control. It would be great to have you work with us. Please do bear the offer in mind.

Best wishes

Chris

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx



I love dry British wit.  You slay me, Chris.

;)

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Offline lysdexia

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Re: Halogen allotropes
« Reply #9 on: 26/12/2004 01:28:54 »
Hey everybody, pay attention to me!  I'm being pedantic!
« Last Edit: 27/12/2004 09:14:50 by Ylide »
 

Offline lysdexia

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Re: Halogen allotropes
« Reply #10 on: 29/12/2004 01:58:21 »
You even removed the chemistry message.  Ylide, why don't you get a life instead of being a brutal dictator on a board that no one else cares about?
 

Offline Ylide

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Re: Halogen allotropes
« Reply #11 on: 29/12/2004 15:50:24 »
quote:
Originally posted by lysdexia

You even removed the chemistry message.  Ylide, why don't you get a life instead of being a brutal dictator on a board that no one else cares about?



Your "chemistry message", aside from being snide, was basically "if you think you're so smart, go Google this one topic."  If you really want to discuss that topic, start a new thread...you were simply being an ass.  If taking control back of a rogue thread is being a brutal dictator, well, welcome to the regime of a moderated forum.  

As for having a life, I'm not the one wasting my time provoking arguments online by pedentically pointing out others' typing/spelling mistakes.  

This discussion is over.

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Re: Halogen allotropes
« Reply #11 on: 29/12/2004 15:50:24 »

 

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