 NPR3− is isoelectronic with phosphine oxides (OPR3) and siloxides ([OSiR3]−), but far more basic.By varying the R groups on P, a variety of ligands with different electronic and steric properties can be produced, and due to the high oxidation state of phosphorus, these ligands have good thermal stability.Many transition metal phosphinimide complexes have been well-developed as have main group phosphinimide complexes.