Structures and stabilities of P5Mg n P5 (n=1-3) compounds containing P5 ligands. Theoretical investigation

The structures and stabilities of P5MgnP5 (n = 1-3) compounds with P5 ligands have been studied using density functional theory (DFT) at the B3PW91, B3LYP and BP86 levels with 6-311+G(2df) basis sets. For the complexes with n = 1 or 2, the staggered cyclo-P5 analogue of mono- or bi-nuclear magnesocene structure lies lowest on the potential energy surface (PES). For the compounds with n = 3, the discrete sandwich structure with trimagnesium sheet between two P5 ligands lies lowest. The natures of Mg-Mg, and Mg-P5 or Mg-P bondings in these unusual structures have been also discussed using natural bond orbital (NBO) and molecular orbital (MO) analyses.