Synthesis and coordination properties of 6,6'-bis(diphenylphosphinomethyl)-2,2'-bipyridine-N,N',P,P'-tetraoxide

The ligand 6,6'-bis(diphenylphosphinomethyl)-2,2'-bipyridine-N,N',P,P'-tetraoxide(7) is prepared by oxidation of the parent phosphine 6,6'-bis(diphenylphosphinomethyl)-2,2'-bipyridine(10). Combination of the oxidized ligand with lanthanide nitrates Ln(NO3)(3) .(H2O)(n) (Ln=La, Pr, Nd, Dy, Er) results in formation of 2:1 metal:ligand complexes, and the molecular structure of one complex, [Nd(7)(2)](NO3)(3) .[(CH3)(2)NC(O)H](2), is described. The compound crystallizes in the monoclinic space group C2/c with a=20.617(4), b=22.736(6), c=18.455(3) Angstrom, beta= 98.35(1)degrees and Z=4. The molecular structure confirms the bis-ligand stoichiometry and shows that the two ligands are tetradentate. The Nd coordination number is eight, and the NO3- ions and solvent molecules are not involved in inner sphere coordination.