Cyanide Ligand Assembly by Carbon Atom Transfer to an Iron Nitride

The new iron(IV) nitride complex PhB($^i$Pr$_2$Im)$_3$Fe≡N reacts with 2 equiv of bis(diisopropylamino)cyclopropenylidene (BAC) to provide PhB($^i$Pr$_2$Im)$_3$Fe(CN)(N2)(BAC). This unusual example of a four-electron reaction involves carbon atom transfer from BAC to create a cyanide ligand along with the alkyne $^i$Pr$_2$N–C≡C–N$^i$Pr$_2$. The iron complex is in equilibrium with an N$_2$-free species. Further reaction with CO leads to formation of a CO analogue, which can be independently prepared using NaCN as the cyanide source, while reaction with B(C$_6$F$_5$)$_3$ provides the cyanoborane derivative