Structure of 1,3,2,6-dioxasilaphosphocines in solution. Experimental and theoretical studies

Steric structure of 1,3,2,6-dioxasilaphosphocines in solution is studied by high-resolution H-1, C-13, P-31, and Se-77 NMR spectroscopy, dipole moment and Ken effect measurements, and theoretical calculations. It is found tha t independent on the coordination of the phosphorus atom (3 or 4) the eight -membered hetero-ring prefers a chair-chair (crown) conformation.