Phosphinalkylene, 50. Zur Struktur von 2,2,2‐Triphenyl‐1,2λ5‐oxaphospholanen

Phosphine Alkylenes, 50. — On the Structure of 2,2,2‐Triphenyl‐1,2λ5‐oxaphospholanes 2,2,2‐Triphenyl‐1,2Δ5‐oxaphospholanes (5a—h) were synthesized from methylene‐triphenylphosphorane (1, R=H) and suitable epoxides (2a—g). Oxaphospholane 5e was subjected to an X‐ray structural analysis, which showed a five‐membered ring‐structure with a trigonal‐bipyramidal coordinate phosphorus atom. One phenyl group and the ring oxygen atom are apical ligands at phosphorus. According to the NMR spectra, oxaphospholanes have a ring structure in nonpolar solvents, whereas in polar solvents there exists an equilibrium with an open‐chain form.