The four title compounds have been synthesized and characterized by ¹H, ¹³C and ³¹P NMR spectroscopy and their identities confirmed by elemental analysis and X-ray crystallography. Bu^t₂P(E)NHPrⁿ [E=Se (1); E=Te (2)] and Ph₂P(E)NHPrⁿ [E=Se (3)] were prepared by the metathesis reaction of LiNHPrⁿ with the appropriate chlorophosphine in diethylether at −78 °C, followed by reaction with elemental selenium or tellurium at reflux temperatures. (1) and (2) are isostructural with PSe 2.1163(14) Å and PTe 2.3642(13) Å. In (3) a PSe bond length of 2.1159(10) Å is observed. (4) was prepared by the additional of two equivalents of diethylchlorophosphine to the dilithium salt of n-propylamine.