Synthesis of new heterocycles 1,3,2,6-dioxaphosphaselenacyclooctanes.

New phosphorus- and selenium-containing heterocyclyes, 1,3,2,6-dioxaphosphaselena-cyclooctanes (la-1h), were synthesized by the reaction of bis(2-hydroxyethyl)selenide with RP(X)Cl2 where R=alkoxyl, aroxyl, aryl and X=O or lone pair. Their structures were determined by spectro-scopies and elemental analyses and finally confirmed by the X-ray crystallographic analysis of 1c. The molecular structures of the heterocycles were discussed in term of conformational analysis.