SYNTHESIS AND MOLECULAR-STRUCTURE OF NEW RING-SYSTEMS FROM 1,1,3,3-TETRACHLORO-1,3-DIPHOSPHAPROPANE

1,1,3,3-Tetrachloro-1,3-diphosphapropane 1 reacts in two different ways to form new heterocycles. Partial oxidation of 1 with tetrachloroorthobenzoquinone furnishes the methylene-bridged lambda3P, lambda5P species 3. Subsequent reactions with di- and triethylamine lead to the condensed ring system 6 with the P=C bonds connected to a central four-membered ring. Compound 6 displays crystallographic inversion symmetry, a short transannular P-P distance and an extremely distorted tetrahedral coordination geometry at the four-membered ring phosphorus atoms. 1 reacts with 7 to give the heterocycle 8 with a central eight-membered ring involving four phosphorus atoms. The eight - membered ring shows a ''bent'' crown conformation, the condensed five-membered rings display envelope conformation.