The nitride ligand can be both electrophilic and nucleophilic. Terminal nitrides of early metals tend to be basic and oxidizable, whereas nitrides of the later metals tend to be oxidizing and electrophilic.  The former behavior is illustrated by their N-protonation and N-alkylation.  Ru and Os nitrido complexes often add organophosphines to give iminophosphine derivatives containing the RPN ligand.