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I really don't know anything about chemistry, but I was wondering about the following vague question: has any substance been created that does not contain any metallic elements, but is metallic? In fact, the only nonelemental metals I know of are alloys, so I may as well ask whether we have ever created any metallic compounds, with or without metallic constituents (without preferred). Both Wikipedia and the tag wiki here claim that metallic compounds do exist but don't give examples.

My vague understanding of what makes an element metallic is that it has something to do with the sharing of electron clouds between atoms, and this question is motivated by wondering whether this kind of quantum effect can be induced from nothing in an appropriately constructed molecule.

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    $\begingroup$ If I understand correctly, you have 3 questions: 1. Are there any compounds created from non-metal elements that behave like metals 2. Is it possible to alloy a non-metal with a metal 3. Do metals form compounds Is that about right? $\endgroup$
    – Tomcat
    Aug 12, 2013 at 5:44
  • $\begingroup$ 1. Yes; 2. No, that was just a comment about what I know about non-elemental metals; 3. No, by "metallic compounds" I meant what you wrote in #1. I understand that metals form compounds (e.g. rust). $\endgroup$
    – Ryan Reich
    Aug 12, 2013 at 6:05
  • $\begingroup$ What properties of metals are you looking for? There are compounds that conduct like metals, shape like metals, have heat capacities/melting points of metals, etc. etc. but I don't know of any that share all the properties that we think of as "metallic." $\endgroup$
    – chipbuster
    Aug 12, 2013 at 7:46

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Metals have several general properties in common (to some degree):

All of these properties derive from the "metallic bond", a delocalized sharing of electrons throughout the metal lattice, which is the key necessity for displaying macroscopic metallic properties. All metals do not behave the same way for these properties. For example, gold is more malleable than iron.

Metalloids are those elements with one or more allotropes that have metallic characteristics. Few if any metalloids display all of the metallic characteristics (otherwise they would be metals!). For example, graphite is lustrous and electrically conductive, but not thermally conductive, malleable, ductile, or fusible. The metalloid with the most metallic behavior is tellurium, which is fusible and ductile.

As for compounds, many are like the metalloids - they have some properties of metals but not all. For example, silicon carbide is lustrous, but that's about it. Otherwise it is hard, brittle, and an insulator.

Polyacetylene and derivative polymers are sometimes call "synthetic metals" because of their electric conductivity and sometimes luster. However, again, they are thermally insulating. They also tend to burn instead of fuse.

Metalloid elements and compounds are not quite metallic because their electron delocalization is in only one (polyacetylene) or two (graphite) dimensions, not all three.

Update!

Based on Snipergirl's comment, it appears that we are closer than I originally thought to preparing true synthetic metals. This highlight at phys-org suggests that supramolecular lattices of redox-coupled conjugated organic ions can exhibit metallic behavior at low temperature. The full article is at Nature Communications and has been made open access. These compounds appear to be close to achieving delocalization in all three dimensions. The behavior of this organic material is not surprising: metals and metalloids become even more metallic at cryogenic temperatures. The induced superconductivity allows for such cool things as magnetic levitation and MRI.

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  • $\begingroup$ Just to add to your excellent answer, check this out: phys.org/news/… ! $\endgroup$
    – Tomcat
    Aug 12, 2013 at 22:35
  • $\begingroup$ This answer explains well what to look for in an artificial metal; I gather from it that the answer to my question is probably "no", though Snipergirl's link is fascinating (and rather timely). $\endgroup$
    – Ryan Reich
    Aug 13, 2013 at 1:18
  • $\begingroup$ @Snipergirl Do you have any details to add on the subject of organic metals? They allegedly share all properties of metals, so conceivable answer my question. $\endgroup$
    – Ryan Reich
    Aug 13, 2013 at 1:18
  • $\begingroup$ I'll need to read the article referenced in the post @Snipergirl linked and look at the data to be certain, but the research looks promising. Conductivity and other metallic properties do increase at cryogenic temperatures. However, neither I nor my institution subscribe to Nature Communications, so it'll be a while for me to get to it. $\endgroup$
    – Ben Norris
    Aug 13, 2013 at 12:30
  • $\begingroup$ Ooh also there was something about metal oxides becoming metallic at high pressures? phys.org/news/2012-08-elusive-metal.html#inlRlv $\endgroup$
    – Tomcat
    Aug 14, 2013 at 13:22
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Carbon Nanotubes and graphene can be metallic in the sense that they conduct electricity very well, they are produced mainly by humans (not seen much in nature), and they are created from carbon, which in it's graphitic form is not very conductive at all.

This answer doesn't answer all of your questions but it takes a small stab at the first.

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