An ab initio study and natural bond orbital (NBO) of the effective factors on the isomerization of halo carbonyl phospha-keten and their analoga containing As atom

The conformational behavior and structural stability of halo carbonyl phosphaketen derivatives (FC(O)PCO) and their analoga containing As atom (FC(O)AsCO), [F-P(1), Cl-P(2), Br-P(3), F-As(4), Cl-As(5), Br-As(6)] were investigated by means of G3MP2, CCSD, MP2 and B3LYP methods set on all atoms and natural bond orbital (NBO) interpretation. Calculations were done using 6-311+G** basis set. All methods showed that the Z-conformations of compounds 1, 2, 3, 4, 5 and 6 are more stable than their corresponding E conformations, but the stability of the Z conformations, when compared with the corresponding E conformations, increases from compound 1 to compound 3 and also from compound 4 to compound 6. The behaviors of compounds 1-6 have been reasonably explained by their generalized anomeric effects (GAE), the electrostatic model associated with the dipole–dipole interactions (EM-DDI), resonance energy and the attractive electrostatic interactions (AEI).The correlations between the generalized anomeric effects (GAE), dipole–dipole interactions, donor and acceptor orbital energies and occupancies, structural parameters and conformational behavior of compounds 1–6 have been investigated.