The data on the synthesis, stereochemistry, and molecular dynamics of alkoxy(ary1oxy)halogenphosphoranes of acyclic structure, as well as of halogenphosphoranes containing the pentacoordinate phosphorus atom in the 1,4,2-dioxophospholane cycle and the node of bicyclo[2.2.2]octane system, are systematized. The influence of spatial properties of polyhalogenalkyl substituents on thermal stability and structure of adducts from tris(po1yhalogenalkyI) phosphites with chlorine and bromine is ascertained. The eflect of the phosphorus atom inclusion into the cycle and node of the bicyclooctane system on its pentacoordinate state stability is investigated.