What is the structure of FOOOF and FOOOOF?

[etotheipi]

FOOF looks like this:

This paper suggests that FOOOF also exists but does not give a structure, although it does state that it's unlikely it takes the F-O-O-O-F structure. "Ignition: An informal history of liquid rocket propellants" claims that this series of compounds, up to FOOOOOOF, can exist.

How can we go about finding the structure of these more exotic species? Thanks!

 

[jim mcnamara]

Hmm. I do not know a resource, but I do not implicitly trust some of what you cited. Stability comes to mind. Are these odd molecules supposed to be stable at STP? Or do they require extreme cold? This:
https://en.wikipedia.org/wiki/Dioxygen_difluoride (where you got your diagram)

says FOOF decomposes at ~(-160°C) Not exactly a kitchen friendly compound.
And it is named for its ability to oxidize and burst into flame almost with anything - it is onomatopoetic 'FOOF' for instant flammability.

 

[jim mcnamara]

A bit more discussion: https://en.wikipedia.org/wiki/Oxygen_fluoride
with some references.

 

[berkeman]

"Ignition: An informal history of liquid rocket propellants" claims that this series of compounds, up to FOOOOOOF, can exist.

And it is named for its ability to oxidize and burst into flame almost with anything - it is onomatopoetic 'FOOF' for instant flammability.

Um, @etotheipi what are you building in your dorm room?

https://www.nationalgeographic.com/content/dam/magazine/rights-exempt/2018/09/pr-rockets/rockets-launch-black-rock-desert-nevada-7.ngsversion.1534392082215.adapt.1900.1.jpg

 

[etotheipi]

shhhhh, if college finds out they'll increase my rent!

 

[TeethWhitener]

A propos of nothing, here’s the always hilarious Derek Lowe on the topic of FOOF:
https://blogs.sciencemag.org/pipeli...3/things_i_wont_work_with_dioxygen_difluoride

 

[PeterDonis]

How can we go about finding the structure of these more exotic species?

The short answer is, you don't unless you have a really, really, really pressing need to, something like a war, and even then you think twice. I suggest reading the Derek Lowe article that @TeethWhitener linked to. Of course, if you've read the "Ignition" book, you have already read hair-raising descriptions of such attempts.

 

[PeterDonis]

I suggest reading the Derek Lowe article that @TeethWhitener linked to.

You might also want to check out the link there to Lowe's article on chlorine trifluoride, which features a priceless quote from the "Ignition" book's discussion of that substance.

 

[TeethWhitener]

More to the point:
https://atct.anl.gov/Thermochemical Data/version 1.122/species/?species_number=935#ref_4
I’ve never personally worked with any of these compounds, but if I were going to try to determine their structure, I’d probably try to perform some sort of matrix isolation spectroscopy on them:
https://en.m.wikipedia.org/wiki/Matrix_isolation
Prepare the oxygen fluorides in situ, co-deposit them with argon on a cold finger and do IR spectroscopy. The matrix may perturb the system, but it’s a heck of a lot safer than anything else I can think of off the top of my head.

 

[etotheipi]

That's cool, haven't heard of that technique before! If I understand correctly, you'd prepare the compound you want to do the IR spec on in situ along with an excess of an inert gas like argon (which is also optically transparent), and then cool the whole thing so that the the argon forms a solid host matrix in which the compound is embedded?

And then, you'd somehow use the vibrational IR absorptions to deduce the structure? I've only covered quite basic IR spec, e.g. different types of stretches, rocking, wagging, that sort of thing (for common functional groups), but I don't know how complicated it is to try and recreate a molecule like this from the spectrum.

 

[TeethWhitener]

If I understand correctly, you'd prepare the compound you want to do the IR spec on in situ along with an excess of an inert gas like argon (which is also optically transparent), and then cool the whole thing so that the the argon forms a solid host matrix in which the compound is embedded?

Yes.

And then, you'd somehow use the vibrational IR absorptions to deduce the structure? I've only covered quite basic IR spec, e.g. different types of stretches, rocking, wagging, that sort of thing (for common functional groups), but I don't know how complicated it is to try and recreate a molecule like this from the spectrum.

In practice, you’d throw the structure (or several candidate structures) into an ab initio program like Gaussian and calculate the IR spectrum, then compare it with the observed IR spectrum.

 

[etotheipi]

In practice, you’d throw the structure (or several candidate structures) into an ab initio program like Gaussian and calculate the IR spectrum, then compare it with the observed IR spectrum.

Oh yeah! I forgot that professional chemists don't waste time assigning spectra by hand

Thanks!