Aromatic 5-silicon rings synthesized at last | Hacker News Reader

Aromatic 5-silicon rings synthesized at last

cen.acs.org

83 pointskeepamovin34 comments

>Move over cyclopentadiene anion—there’s a new five-membered aromatic ring in town, and this one is made of silicon.

CHEM-Es are build a little different from the rest of us.

Cyclopentadiene is a great molecule - it can form 'metallocene' compounds where two cyclopentadiene (Cp) rings 'sandwich' a metal ion between them:

https://en.wikipedia.org/wiki/Metallocene

Like Cp--M--Cp where the '--' are an unusual kind of 'bond' which is somewhat like five carbon-metal bonds, although I'm sure there is a more accurate orbital description of the interaction.

The ‘--‘ is a ligand bond, a fundamental aspect of coordination and organometallic chemistry.

"The average person probably only knows the formulas for olivine and one or two feldspars" (https://xkcd.com/2501)

Perfect! I read this “heart-warming” overview of two papers in Science and learned zero about why this is of any significance. The discovery is significant but I had to probe Opus 4.6 to find out why.

The personal focus is a distraction. It would be great if science writers could focus on the science and significance of the advance.

Not sure why you were downvoted. I love the breathless enthusiasm of the article, but I still have no idea why (or if) this is important. What did you learn from Opus?

And quartz of course.

Chemists really. Chem-E’s basically just play IRL Factorio at work. The graphs in Factorio look almost exactly like OSI PiSoft charts, which basically every chemical plant uses.

Nah, this is just a strict chemical synthesis problem, no need for the engineers yet, until you want to make ten thousand tons of the stuff.

Dilithium is a real thing. Who knew?

https://en.wikipedia.org/wiki/Dilithium

It's indispensable when dealing with self-sealing stem bolts

Or a lot of yamok sauce.

The reason this is important is not because the molecule has any practical utility, either now or in the future. Most of the reactions it participates in will probably be various decompositions of itself into other. The real importance comes from what this molecule can teach us about the laws of nature--why Si is the way it is, so distinct from carbon. Specifically, how do the valence electrons of Si manage in a 5 member ring? What does that wave-function look like, and does it agree with our predictions? Do we understand this corner of the universe as well as we think we do? Orbitals are tricky things to compute, so we need difficult to construct molecules to test our calculations.

Any possible applications?

> Iwamoto and Scheschkewitz say pentasilacyclopentadienides could be ligands for catalysts and materials.

The review should have expanded on this at a practical level even mom and dad could understand—the standard “better life through chemistry” angle.

Sounds like it could improve the production efficiency of glyptal-impregnated, cyanoethylated bushings for turbo-encabulators!

So what was their aroma like?

In this case aromatic means a ring of atoms where there is electron sharing among all the members of the ring.

They're called aromatic rings because before they understood the structure, they grouped them by their behavior, and the aromatics contain a lot of volatile organics like benzene, toluene, phenol, which have strong odors.

I like your explanation without condescension. Respect.

https://xkcd.com/1053/

So it's not volatile enough to give off a scent?

Massive molecule with a lithium salt on every silicon atom. It's not going to have basically any vapor pressure and thus effectively no aroma unless there are breakdown products

Even if it were volatile, you likely wouldn't be able to smell it. The olfactory sense is complicated and weird, and targeted at organic chemistry. You can smell a few inorganic things (notably, elemental osmium, whose name literally means "smell" because that's so unusual), but your receptors are unlikely to trigger for anything that far removed.

Doesn't this count as organic? Ferrocene smells of camphor, apparently. https://pubchem.ncbi.nlm.nih.gov/compound/ferrocene

It is organic; it's mostly carbon. The presence of a metal atom doesn't make it inorganic. To be inorganic it has to have no carbons (or at least, not in the backbone of the molecule).

Plain cyclopentadiene is way stronger smelling than any of those.

Also dicyclopentadiene which is a higher-"boiling" dimer which often serves as a source of cyclopentadiene by thermal breakdown. The DCPD solidifies at lower room temperatures. It also spontaneously decomposes to an extent so what you are smelling is probably the CPD anyway.

General agreement technically is that DCPD is some nasty-smelling shit, one drop on your foot and the shoes are staying outside for the night :\

Interestingly, in very low concentrations it is used in some fragrances as a once-secret ingredient.

Well yes, but also what do they smell like?

"Characteristic", no doubt.

If you know, you're probably dead.

So, we have a chance to reduce our usage of volatile hydrocarbons. Silicon-based chemicals should not burn as easily as CH-based ones.

This particular silicon compound is unlikely to help much in that direction.

On the other hand, silicone resins and elastomers are already in widespread use in applications where resistance to high temperatures or burning is required (silicone =/= silicon, the former coming from silic-on + ket-one, a name based on a wrong hypothesis).

However, their mechanical resistance is usually modest, so if that is important they must be used either in combinations with other materials or reinforced, e.g. with glass fiber.

They are also more expensive than hydrocarbon-based plastics, so they are typically used only where strictly necessary.

No, it's a super weird molecule that is big, expensive to make and probably form a solid. It can not replace solvents like benzene.

The weird structure of the electrons in the silicon cycle may be useful as a catalyst(or not, it's too early to be sure). Imagine it is like the Platinum in the car exhaust, not the solvent in the paint remover.

Methane (CH4) is the simplest hydrocarbon and the primary constituent of natural gas.

Even though it is not waxy it is also considered a paraffin. Like other paraffins it is largely inert except for that one little reaction with oxygen where it burns readily releasing great energy. But that usually requires contacting a spark or flame or there is no reaction.

The silicon analog is silane (SiH4), it spontaneously combusts quite easily without any spark at all.

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