The curious case of cubane

Image Credit: NEUROtiker (Own work) [Public domain], via Wikimedia Commons
Image Credit: NEUROtiker (Own work) [Public domain], via Wikimedia Commons
Cubane was never supposed to exist. Deemed impossible to synthesize due to predictions that it would be extremely unstable, hypotheses about cubane’s strange properties were long confined to the realm of speculation. But in the early 1960s, researchers Philip Eaton and Thomas Cole at the University of Chicago made the risky decision to attempt the synthesis—and they succeeded.1,2 Half a century later, the researchers’ reports describing how to trap the capricious compound continue to spawn new discoveries, many of which they could never have anticipated.

Early predictions of cubane’s tremendous instability and unique properties alike stemmed from its shape. The bonds between the carbon atoms that represent each corner of the cube are all separated by just 90 degrees, far from the ideal 109.5 degrees. Forcing the carbon atoms into this immensely strained geometry shouldn’t be impossible per se, but it should be about as difficult as bending a cast iron skillet with your bare hands. If the challenge of coercing the atoms into such a strained shape alone didn’t lead early investigators to consider cubane’s synthesis impossible, the likely instability of the product would probably have discouraged them. If a substance decomposes before anything can be done with it, potentially causing a dangerous explosion in the process, why even attempt to make it?

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