Synthetic, spectroscopic, and structural studies on lanthanide complexes of diphosphazane dioxide ligands

Abstract

Lanthanide nitrate complexes of diphosphazane dioxides Ph₂P(O)N(Prⁱ)P(O)Ph₂ (1) and (PhO)₂P(O)N(Me)P(O)(OPh)₂ (2) have been synthesised and studied by conductometry, IR, multinuclear NMR spectroscopic methods and X-ray diffraction. Ligand 2 is accessible by two different methods, viz., by direct oxidation of the phosp(III)azane ligand or by starting from phosph(V)azane chloro precursor. The structure of 2 is confirmed by X-ray diffraction. Crystallographic data for 2: Triclinic, Space group P1, a = 10.078(1), b = 10.575(3), c = 12.364(4) Å, α= 75.70(2)°, α= 75.56(1)°, γ= 77.68(1)°, Z = 2, V = 1 220 ų; structure refined to RF = 0.0459 on 3 495 data with F > 3s(F). The diphosphazane dioxide ligand exhibits trans geometry in the solid state. The structure of a lanthanide complex, [Pr(NO3)3(2)2] (14) is also determined by X-ray diffraction. Crystallographic data for 14: Trigonal, Space group P3₂, a = b = 15.710(2), c = 40.067(2) Å, Z = 6, V = 8 564 ų; structure refined to RF = 0.0430 on 8 077 data with F > 5σ(F). The two diphosphazane dioxide ligands and the nitrate groups are coordinated to praseodymium in a bidentate chelate fashion. The geometry around the ten coordinated metal is distorted bicapped square antiprism.