The closest chemists have ever got to an inorganic ferrocene

An iron ion sandwiched between two cyclotetraphosphide dianions is the closest analogue to an inorganic ferrocene ever created.

When ferrocene was discovered in the early 1950s, it caused quite the stir. It was the first compound made only of a transition metal and a hydrocarbon that didn’t spontaneously decompose or burst into flames when it met air or water. Since then it has become the poster child of organometallic chemistry.