Iron and Palladium Complexes of Pacman Phosphanes

Pacman phosphanes, which can be regarded as multidentate macrocyclic ligands with two P-donor centers, were used for the synthesis of palladium and iron complexes. The isolation and complete characterization of Pd(0)-, Pd(II)-, and Fe(II)-Pacman phosphane complexes were achieved. While the Pd complexes formed both mononuclear and binuclear distorted planar complexes, distorted octahedral environments were observed in the iron complexes. Depending on the substituent on the phosphorus atoms, either a diamagnetic low spin iron(II) complex or a paramagnetic high spin iron(II) complex was found. The electrochemical investigations of the iron(II) complexes showed three redox events, with the first being both electrochemically and chemically reversible. The structure and bonding of all Pacman phosphane complexes is discussed on the basis of single-crystal X-ray studies and quantum chemical computations.