Synthesis, Characterization, and Coordination Chemistry of a New Geometrically Hindered Trifunctional Ligand, 4,5-Bis(diphenylphosphino)-<i>sym</i>-octahydroacridine <i>N</i>,<i>P</i>,<i>P</i>‘-Trioxide

The ligand 4,5-bis(diphenylphosphino)-sym-octahydroacridine N,P,P‘-trioxide (10) was obtained from a multistep synthesis and characterized by spectroscopic methods, and two crystal forms were examined by single-crystal X-ray diffraction techniques. The coordination behavior of the trifunctional ligand toward La(NO3)3 and Nd(NO3)3 was examined, and the molecular structures of the complexes La(10)(NO3)3·MeOH and Nd(10)(NO3)3·MeOH were determined by single-crystal X-ray diffraction methods. The molecules form chains along the z axis in which the ligand bonds in a bidentate mode to one La(NO3)3 or Nd(NO3)3 by using the N−O and one of the PO donor centers. The second PO donor group in the ligand bridge bonds to a second La(10)(NO3)3 or Nd(10)(NO3)3 unit. The coordination behavior of 10 contrasts with that of the related but structurally more flexible trifunctional ligand 2,6-bis[(diphenylphosphino)methyl]pyridine N,P,P‘-trioxide, which acts as a tridentate ligand toward f-element ions.