A Theoretical Study on Applying Conformational Analysis of 2-Halo-2-Oxo-1,3,2-Dioxaphosphorinanes

The quantum-chemical calculations on the conformational properties of 2-flouro-2-oxo- 1,3,2-dioxaphosphorinane (1), 2-choloro-2-oxo-1,3,2-dioxaphosphorinane (2) and 2 bromo- 2-oxo-1,3,2-dioxaphosphorinane (3) have been investigated by means of ab initio molecular orbital (HF/6-311**) and hybrid density functional theory (B3LYP/6-311**) based methods and Natural Bond Orbital (NBO) interpretation in solid state was performed. Geometrical analysis supports clearly the participation of hyperconjugative endo-anomeric (LPO→σ*P-X) effect in the stabilization of axial series of compounds and the participation of exo-anomeric (LPX→σ*P-O) effect in the stabilization of the equatorial phosphinanes in chair conformations. The stereoelectronic effects associated with bonding-anticoding delocalization electron are more significant for the explanation of the conformational behavior of compounds 1-3 than the dipole-dipole interaction effects.