An accidental molecule – ferrocene

What does it look like?

What is it?

Ferrocene was (like many things) discovered by accident. Two groups, working independently, were both looking for something else when they in fact made an orange powder that they didn't expect. Both knew that it was made from an iron atom and two cyclopentadiene (five carbon atoms joined together with hydrogens attached), but thought that they would sit aligned in a solid together.

But X-ray crystallography showed that that was wrong, and the ferrocene molecule takes up a 'sandwich' structure with the two cyclopentadiene rings either side of the iron atom. This remarkable discovery also revealed the strange properties of this material, and paved the way for the subsequent rapid growth of organometallic chemistry.

Where did the structure come from?

You can read more about the history of the structure of ferrocene from an excellent C&EN article here. The structure we've plotted today is actually a high-temperature form of ferrocene, and is #210932 in the Crystallography Open Database.

Tags: iron   molecular   organometallic chemistry   ferrocene