Synthesis and Coordination Properties of New Bis(phosphinomethyl)pyridine <i>N</i>,<i>P</i>,<i>P</i>‘-Trioxides

In a search for more hydrocarbon solvent soluble derivatives of the parent ligand, 2,6-[Ph2P(O)CH2]2C5H3NO (1a), a series of new ligands, 2,6-[R2P(O)CH2]2C5H3NO [R = Bz (1b); Tol (1c); Et (1d); Pr (1e); Bu (1f); Pn (1g); Hx (1h); Hp (1i); and Oct (1j)] and 2,6-[RR‘P(O)CH2]2C5H3NO [R = Ph, R‘ = Bz (2a); R = Ph, R‘ = Me (2b); R = Ph, R‘ = Hx (2c); R = Ph, R‘ = Oct (2d)], have been prepared by either Arbusov or Grignard substitutions on 2,6-bis(chloromethyl)pyridine followed by N-oxidation. The new ligands have been characterized by spectroscopic methods, and their coordination chemistry with selected lanthanide ions has been surveyed. Several 1:1 and 2:1 ligand/metal complexes have been isolated, and single-crystal X-ray diffraction analyses for Nd(2a)(NO3)3, Er(2a)(NO3)3, Yb(1d)(NO3)3, and [Nd(1c)2](NO3)3 are described. The new structural data are discussed in relation to the structures of complexes formed by 1a.