Spatial structures of phosphorus-containing heterocyclic compounds - XXIV. Conformations of 2-X-4,5,6,7-dibenzo-1,3,2-dioxaphosphepanes

1. 2-X-4,5,6,7-Dibenzo-1,3,2-dioxaphosphenanes (X=Cl, OEt, OPh) have a twist form, and angle of twist with respect to the biphenyl bridge is equal to 41-48°. 2. The ethoxy radical in these compounds is characterized by a gauche orientation with respect to the P-O bond, and the phenoxyl group has a cis conformation. © 1981 Plenum Publishing Corporation.