An ab initio study of the ligands diphosphinoamine and diphosphinomethane in the chelating and bridging geometries

A study of the energies of the model compounds diphosphinoamine (dpa) and diphosphino-methane (dpm) as a function of the P-E-P (E = N and C respectively) bond angle was conducted using ab initio methods at the MP4SDQ/6-31G∗//RHF/3-21G∗ level. Equilibrium structures of C2v and Cs, symmetry were obtained for both compounds. The compounds were found to exhibit a very similar angular dependence of their potential energy. The difference in destabilization between dpa and dpm as they are distorted from their equilibrium geometries to any angle ø emanates from the difference in their equilibrium P-E-P bond angles.