A comparison of analogous 4f- and 5f-element compounds: syntheses and crystal structures of triphenylphosphine oxide complexes of lanthanide(III) and uranium(III) triflates and iodides [MX 2(OPPh 3) 4][X] (X=OTf and M=Ce or U; X=I and M=Nd, Ce, La, U)

Abstract

The X-ray crystal structures of the title complexes show that the differences between the U–O and Ln–O distances reflect the variation in the ionic radii of the trivalent uranium and lanthanide ions while the U–I bond lengths are smaller than those predicted from a purely ionic bonding model. The results indicate that the uranium ion interacts more strongly than the lanthanide ions with the softer iodide ligand, and that the counterions would have a major influence on the differentiation of trivalent 4f and 5f ions.