Oddball compound

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Special polymers

Polymeres are not the main interest in advanced atomically precise manufacturing since they are not stiff and diamondoid. Some of them may be useful in the early stages of the path to APM. They may play some role in some products of advanced atomically precise technology though like in entropomechanical energy converters. Introducing polymers into advanced AP systems (that are mainly crystolecule based) means introducing weak spots. Radiation and heat have a higher chance to break a long chain than a solid crystolecule brick. See: Consistent design for external limiting factors

  • Inorganic polymers: Usually not found in nature. They can have some unusual properties
  • Conductive polymers: Common polymers are usually electrically isolating. Conductive polymers might be useful in early stages of bootstrapping of APM (e.g. for electrostatic actuation)
  • Artificial foldamers (the name implies their defining self folding property): beside common biological foldamers artificial foldamers are very likely to play a major role in the development of advanced APM (gem gum technology).
  • Polymers with combinations of the precedingly described properties.

Unusual transition element oxides

Transparent volatile liquid metal oxides (/rusts). Note that those are highly toxic.

Despite an excess of metal atoms to oxygen atoms the compound is non-metallic and transparent:

Unusual transition element sulfides

Most metal sulfides are metallic and non transparent.
Think: Pyrite FeS (cubic), Galena PbS, Troilite FeS (hexagonal), …
Exceptions:

  • Wurtzite ZnS being transparent as a clean single crystal

Rather inert compounds with fluorine

  • SF6 Sulfur hexafluoride [1] – so unreactive that it can be breathed in without harm (not to recooment though)
  • NF3 Nitrogen trifluoride [2] – somewhat reactive but way less than what may be expected
  • CF4 Carbon tetrafluoride [3] (more commonly known as tetrafluormethane) – pretty darn inert
  • And all the perfluorocarbons: (PFCs)

This flips quick to highly reactive and toxic though:

  • OF2 oxygen difluoride [4]
  • PF3 phosphorus trifluoride [5]
  • SiF4 [6] hydrolyzing to F6H2Si [7] – (a salt: Na2[SiF6] [8])

Interestingly in the chalcogen group it's flipped the heavier element makes the (by far) more stable compound.
In the other cases the lighter elements make the more stable compounds.

Other compounds with unusual properties

Carbon suboxide has a low energy state in earth’s oxidative environment and can be polymerized to a solid that could easily be stored by today’s means. When chemomechanical converters will become available there most likely will be better storage methods for depleted energy available though. So its just a curiosity. Note: Somewhat unintuitively the compound C2O2 (ethylene dione) is very unstable. It has a short lifetime even at low temperatures. This is one of the more subtel instances where one can see that the "periodic table as construction kit" metaphor must often be taken with a grain of salt.

High oxides

Highly oxidizing acid anhydrides:

  • Dichlorine hexoxide Cl2O6 [9]
  • Iodine pentoxide I2O5 [10]
  • Some other pentoxides [11]

Compounds dominantly containing nitrogen

Those are usually quite unstable to explosive.

Compounds containing a lot of carbon dioxide

  • Weddellit – calcium oxalate with two waters – Mohs 4 – [12]
  • Whewellit – calcium oxalate with one water – Mohs 3 – [13]


Polymers: Polycarbonates with small linkers like:

  • polypropylene carbonate PPC [14]
  • polyethylene carbonate PEC – rare but available commercially empowermaterials
  • polymethylene carbonate??

Compositon wise this is almost polymerized carbon dioxide.
Could this be used as CO2 sink?

Others

Grey α-tin: Tin has a fully nonmetallic form that takes on the more sparse crystal structure of silicon due to covalent bond coordination. Replacing some silicon atoms in a silicon oxide (quartz) or silicon carbide crystal with tin is likely to lead to stable structures with maybe desirable properties. Or reversely how much modification by substitution does α-tin need to become more stable, that is to loose its self decompositional properties on thermal cycling? Maybe mechanosynthesized crystalline α-tin is even stable as long as it's not molten up?
https://en.wikipedia.org/wiki/Tin_pest

Xenon dioxide: Under high pressure xenon supposedly can replace silicon in quartz. It is believed that the theoretically predicted amount of Xenon that is missing in our atmosphere is trapped this way inside the earth. https://en.wikipedia.org/wiki/Xenon_dioxide Highly localized pressure (strained structures) can make (single or multiple substitutions of silicon with xenon) stable at macroscopic ambient pressures. Xenon is not too abundant so large scale structural applications (whatever they are) are not likely to become widespread.

Misc

1,3,5-Trithiane – Wikipedia: [15]
A six membered carbon sulfur alternating heterocycle. Only slightly soluble in water. Slightly toxic.
Maybe a candidate for resource molecules but there are probably better ones.

Carbon monoxide privatizations on metals aka metal carbonyls.
Like e.g. in nickel tetracarbonyl. This one is particularly toxic and problematic.

Excessive amounts of hydrogen yet stable at normal conditions:
Potassium nonahydridorhenate K2ReH9

Related

External links

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