For the first time, scientists have managed to remove the lone pair of carbene and isolate the resulting doubly oxidised molecule, US researchers report in Nature.

The synthesis itself is relatively straightforward. You start with an electron-rich bis(imino)carbene. First, you react the carbene with I2 and NaOSiMe3 to form a bis(imino)carbonyl. When you add triflate anhydride, this molecule removes the oxygen atom together with its electrons, leaving you with the doubly oxidised carbene2+. The nitrogenous side groups provide the C atom with the necessary electron density to make the whole thing stable.