CIS AND OR TRANS DIOXAPHOSPHETANES - A MOLECULAR-ORBITAL STUDY OF SOME MODEL (RPO)(2) SYSTEMS/

Ab initio RHF/3-21G and MNDO molecular orbital calculations have been performed on model 1,3,2,4-dioxadiphosphetane (RPO)(2) four membered heterocyclic systems. For all substituents tested (R = H,:F, Cl CH3, O H, NH2, BH2, CF3), the bent, cis conformation of the ring is preferred over the planar, trans arrangement. The rhombohedral shape of the rin g with acute OPO angles is a consequence of the P....P transanular int eractions.