Synthesis, Characterization, and Coordination Chemistry of a New Geometrically Hindered Trifunctional Ligand, 4,5-Bis(diphenylphosphino)-sym-octahydroacridine N,P,P‘-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(NO 3 ) 3 and Nd(NO 3 ) 3 was examined, and the molecular structures of the complexes La( 10 )(NO 3 ) 3 ·MeOH and Nd( 10 )(NO 3 ) 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(NO 3 ) 3 or Nd(NO 3 ) 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 )(NO 3 ) 3 or Nd( 10 )(NO 3 ) 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.