PHOSPHORUS-CONTAINING PODANDS .11. SYNTHESIS OF BIS(ORTHO-DIPHENYLPHOSPHINYL)BENZYL ETHERS OF OLIGOETHYLENE GLYCOLS AND THEIR COMPLEXING PROPERTIES WITH RESPECT TO ALKALI-METAL CATIONS

A number of monopodands having o-diphenylphosphinyl terminal groups we re synthesized by alkylating sodium derivatives of oligoethylene glyco ls with o-(bromomethyl)phenyldiphenylphosphine. The stability constant s of the complexes of these ligands with alkali metal cations at 25-de grees-C were determined conductometrically in a THF-chloroform solutio n (4:1, v/v). The complexing ability of monopodands with respect to th e cations studied increases monotonically as the number of electron-do nating sites increases (from 3 to 8) for all of the cations except Li and, to some extent. Na+. In the case of Li+ a smooth decrease in the stability of the complexes is observed. The monopodands obtained in t his work differ drastically in this regard from their structural isome rs, bis[o-(diphenylphosphinylmethyl)phenyl] ethers of oligoethylene gl ycols, which had been studied previously.