The trifunctional ligand, 2,6 bis(diphenylphosphorylmethyl) 4 methylphenol (L 2 ), forms complexes with cerium(III) nitrate having a ligand to metal ratio of 1 : 1, 2 : 1, and 3 : 1. The structures of these complexes in the solid state and in solution were studied by X ray diffrac tion, IR and NMR ( 1 H and 31 P) spectroscopy, and conformational analysis (molecular me chanics). The 2 : 1 complexes of L 2 with lanthanum(III) and neodymium(III) nitrates were synthesized and characterized. In all complexes, the neutral ligand is coordinated through both phosphoryl oxygen atoms. The hydroxy oxygen atom is coordinated only in some complexes, and the hydrogen atom of the hydroxy group is involved in hydrogen bonding. The composi tions and structures of the resulting complexes depend on the method of synthesis and the nature of solvent. The ligand was found to undergo easy inner sphere oxidation. The structure of one of the transformation products was established by X ray diffraction. Unlike the coordi nated ligand, the free ligand is very stable to oxidation.Bis and polyphosphoryl compounds containing an aromatic moiety and the phosphorylmethyl groups in the ortho and meta positions of the benzene ring are conve nient extractants for separation of transuranium and rare earth metals from aqueous solutions of nitric acid. 1-6 In particular, reagents L 1 containing substituents in the meta positions exhibit high separation factors ( f ) with respect to the Eu III /Am III pair. However, the absolute partition coefficients D = [M] org /[M] aq are small.
R = Ar, Alk, AlkOModified ligand L 2 containing an additional coordi nating center in the second position of the benzene ring would be expected to exhibit the coordination and extrac tion properties analogous to those of L 1 , because the main ligand contour remains unchanged. At the same time, additional coordination of the phenolic OH group should increase stability of the extracted complexes and, conse quently, increase the extraction coefficients with reten tion of the selectivity level typical of L 1 , because the phos phoryl groups will remain the main coordinating centers. Actually, already our first experiments on extraction of U VI , Am III , and Eu III from aqueous solutions of nitric acid with solutions of L 2 in dichloroethane have showed 7 that the efficiency of extraction (D) increases by an order of magnitude compared to that of the prototype, viz., dioxide L 1 (R = Ph), the separation factor of the met als ( f ) remaining the same (more detailed data will be published elsewhere).Coordination chemistry of ligand L 2 is poorly known. Only two 1 : 1 complexes with erbium 8 and cerium 9 ni trates were characterized.In the present study, the coordination ability of L 2 was studied using complexation with cerium(III) nitrate as an example. The 2 : 1 complexes with neodymium(III) and lanthanum(III) nitrates were examined in less detail. Here, we report only data necessary for comparison. Since the resulting complexes are unstable during storage, we stud ied also the...