Nature Chemistry | The Sceptical Chymist

IUPAC ’09: Save the symbol!

Remember the latest addition to the periodic table, copernicium, element 112? Well the fall out from the name choice has begun.

The abbreviated symbol that discoverer Sigurd Hofmann chose was Cp. This hasn’t been confirmed by IUPAC yet, and this is the body that has the say in the end, but it seems appropriate that here at the IUPAC congress that the discussion over this shortened symbol should be aired.

The problem is that for many synthetic chemists Cp already means something – it is used as a shorthand form for the cyclopentadienyl ring, a 5 carbon and 5 hydrogen ring that is aromatic like benzene and often used as a ligand.

So some chemists are inevitably unhappy about the use of Cp for another purpose. One of these is Paul Chirik from Cornell University who in his talk about main group chemistry apparently said he wanted to start a campaign to have the abbreviation Kp, not Cp used for element 112. This, apparently is etymologically correct, because Copernicus was actually Polish and his name was spelled Mikolaj Koppernigk.

Chirik assures me he said this in jest and is by no means an expert in this area. But I wholeheartedly encourage this kind of campaign! Come on chemists, stand up for the rights of cyclopentadienyl ligands! Kp vs Cp – what do you think?


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    Jyllian said:

    Would people then confuse the element Kp and the equilibrium constant Kp(*)?

    I suppose, though, that the contexts in which the two are used would help to differentiate. Equilibrium constants shouldn’t turn up in the middle of a chemical formula.

    • The p for the equilibrium constant should be subscript, of course. When I previewed the comment, the subscript tags didn’t appear to be working.
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    Neil said:

    [I don’t think the blog lets us use subscript – I tried sub and inf and neither worked. Sorry!]

    I agree that context is the key, which is also why I’m not soooo bothered about Cp. It’s going to take a long time before organometallic chemists get their hands on enough of it to stick it between any Cp rings!