Strongly donating ligands that enforce three-fold symmetry allow for the isolation of first row transition metal complexes containing metal-ligand multiple bonds. These include isolable tris(carbene)borate iron(IV) and iron(V) nitrido complexes. These complexes are active in nitrogen atom transfer reactions that involve the transfer of up to four electrons. A number of reaction pathways are observed for two electron atom transfer reactions, including multi-state reactivity leading to the formation of aziridines. In contrast to nitrogen atom transfer, [PR] group transfer can occur without the formation of a metal ligand multiple bond.