A stable (amino)plumbylene-substituted phosphaketene 3 was synthesized by the successive reactions of PbCl2 with two anionic reagents (lithium amidophosphine and NaPCO). Of particular interest, the thermal evolution of 3, at 80 °C, leads to the transient formation of corresponding amino- and phosphanylidene-phosphaketenes (6 and 7), via a reductive elimination at the PbII center forming new N−P and P−P bonds. Further evolution of 6 gives a new cyclic (amino)phosphanylidene phosphorane 4, which shows a unique reactivity as a phosphinidene. This result provides a new synthetic route to phosphinidenes, extending and facilitating further their access.