Sciencemadness Discussion Board

Ferrate complexes

Yorty2040 - 6-4-2024 at 12:21

I've been wondering if anyone has done any work on metal-ligand-ferrate complexes as energetics? They're unlikely to be practical, but might be an interesting synthetic challenge.

Ferrates are unstable below ph8, limiting how they can be synthesized, and oxidize ammonia rapidly, making it difficult or impossible to make ammine complexes. They're usually made by combining ferric oxide with sodium hypochlorite in aqueous solution, or in the solid state by burning iron filings with nitrate salts.

Since ferrate would likely destroy ammonia or hydrazine on contact, a less-easily oxidized fuel like urea or glycine would be a better bet.

So a procedure I'm thinking of would be to burn iron filings with anhydrous nickel nitrate to create nickel ferrate, then dissolve it in absolute ethanol and mix with an ethanolic solution of urea or glycine. My concern would be if ferrate would oxidize either the ethanol or the ligand rather than react cleanly; does anyone know?

Yorty2040 - 8-4-2024 at 20:17

On further looking it doesn't seem like nickel ferrate (or any other d-block metal ferrate) exists; the oxidizing power of the anion is just too strong.

Perhaps a binary mixture of sodium ferrate and an organic solid fuel might be detonable?

dettoo456 - 9-4-2024 at 20:10

I don’t know how detonatable they’d be, likely just a thump (moderately strong deflagration) at best. Ex&F made some peroxochromate complexes before on YT and such complexes, even when mixed with strong fuels Red P just couldn’t perform very well due to the solid products of decomposition. The same goes with S4N4, Boron-based energetics, bismuth-based energetics, and phosphazenes - the products are either solid, liquid, or gaseous but have too high energy of formation to form in the combustion (SO2). And because of those solid and liquid products, the force required to propel them and propagate the detonation wave is greatly increased, which decreases the overall rate of detonation or deflagration.

In the case of ferrates, surface oxidation of the particle to iron oxide would greatly hinder any further interactions of the inner portion of the particle to be reduced further. This effect is seen in Al to a lesser degree and much more so in Boron, which requires extremely high heat and aggressive reducers to bring out its full potential use as a fuel in EMs.

If you want a synthetic challenge, maybe ferrocene species like ferrocenium-2-THF could prove interesting. It’s apparently a pretty good burn rate modifier:



[Edited on 10-4-2024 by dettoo456]

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Tdep - 10-4-2024 at 16:52

There's certainly a barium ferrate that is easy to isolate, but it doesn't seem very energetic.
https://www.youtube.com/watch?v=GcgBiDM9tE8

Rather than transition metal salts of ferrate, I wonder if there's any heavy metal ferrates? Of course silver comes to mind first. The reaction conditions may make it impossible, or maybe just difficult? And I suppose what even is the point.... but making an energetic out of iron seems a fun challenge at least

[Edited on 11-4-2024 by Tdep]

EF2000 - 10-4-2024 at 22:27

Quote: Originally posted by Tdep  

Rather than transition metal salts of ferrate, I wonder if there's any heavy metal ferrates? Of course silver comes to mind first. The reaction conditions may make it impossible, or maybe just difficult? And I suppose what even is the point.... but making an energetic out of iron seems a fun challenge at least

[Edited on 11-4-2024 by Tdep]

Rapid Chemical Synthesis of Four Ferrate(VI) Compounds
According to that Iranian paper, ferrates of lead, zinc, cadmium and mercury exist and are relatively stable. They are made by grinding potassium ferrate with metal acetates (for Pb and Zn) or nitrates (for Cd and Hg). All those ferrates are insoluble in water and can be stored at room temperature for more than a month.

About silver ferrate, there is a paper in Electrochemistry Communications (cited by Iranian paper): 10.1016/j.elecom.2005.06.008. Silver ferrate is prepared by adding pure potassium ferrate to solution of silver nitrate in cold triply deionised water. It would be interesting to try grinding potassium ferrate with silver nitrate, to see if solid-state method also works.

Also, searching for silver ferrate, I found that: Silver ferrite: a superior oxidizer for thermite-driven biocidal nanoenergetic materials.

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EF2000 - 12-4-2024 at 07:33

Quote: Originally posted by dettoo456  

If you want a synthetic challenge, maybe ferrocene species like ferrocenium-2-THF could prove interesting. It’s apparently a pretty good burn rate modifier:
[Edited on 10-4-2024 by dettoo456]

If the patent is honest, it increases burn rate more than 6 times, in "Example II". It's really impressive (though burn rate isn't everything).

Beta-ferrocenoylpropionic acid, required for synthesis, can be prepared by a Friedel–Crafts acylation of ferrocene with succinic anhydride. Paper in JACS (doi:10.1021/ja01570a028) reports 87% yield (page 4, don't confuse with ferrocenylpropionic acid on page 3).

Ferrocene itself is prepared from iron(II) chloride and cyclopentadiene. OrgSyn describes 2 methods: https://orgsyn.org/demo.aspx?prep=CV4P0473

But, as someone wise said, not everyone wants to be a cosmonaut. More simple iron compound are also good catalysts. Interesting area for research is soluble iron salts. For example, 1% of iron(II) gluconate in KNO3/sorbitol propellant increase burn rate by 25%, according to amateur rocketeer Scott Jolley: http://www.ajolleyplace.com/additive.html.
Iron(II) ascorbate would be interesting to try, as ascorbates are very good fuels.
I've been obsessing over rockets lately, sorry for veering off topic of ferrates

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