Insertion of a PCH2P unit into p-tert-butylcalix[4]arene, 1, via (Me(2)N)(2)PCH2P(NMe(2))(2) gives the R,S isomer of the "half-substituted" species, 6. Subsequent heating yields the full-substituted derivative 7. The phosphorus atoms of 7 can be oxidized to give 8 and 9. Treatment of 6 with phenyl azide, iodomethane, and tetrachloro-1,2-bezoquinone led to reaction at only one phosphorus to give monoimino, -phosphonium, and -phosphorane compounds, respectively Unexpectedly, the reaction of 6 with tris(dimethylamino)phosphine yielded (Me(2)N)(2)PCH2P(NMe(2))(2) and a six-coordinate phosphorus derivative.