The first terminal rhenium phosphinidene complex, [Re(CO)5(η1-PNiPr2)][AlCl4], has been synthesized by chloride abstraction from [Re(CO)5{P(Cl)(NiPr2)}]. The electrophilic character of the terminal phosphinidene ligand is demonstrated by phosphine addition at the unsaturated phosphorus center and by novel reactions with azobenzene, PhN&dbd;NPh, which generate, via C−H activation and P−N and P−C bond formation, coordinated benzodiazaphosphole ligands. The cations [Re(CO)5P(PPh3)NiPr2]+ and [Re(CO)5{P(PhNNHC6H4)NiPr2}]+ have been crystallographically characterized as their AlCl4- salts. The corresponding late-metal terminal phosphinidene complexes [Co(CO)3(PR3)(η1-PNiPr2)][AlCl4] (R = Ph, Et) also afford coordinated benzodiazaphospholes via reaction with PhN&dbd;NPh.