Synthesis and Structure of Complexes of Np(V) Benzoate, o-Fluorobenzoate, and p-Fluorobenzoate with 1,10-Phenanthroline

Abstract

The structures of three new Np(V) complexes [(NpO₂)₂(phen)₂(C₇H₅O₂)₂] (I), [(NpO₂)₂(phen)₂. (o-C₇H₄FO₂)₂] (II), and [(NpO₂)₂(phen)₂(p-C₇H₄FO₂)₂] (III), where phen = 1,10-phenanthroline, were studied. Two NpO₂⁺ cations in the complexes are bound to each other by cation-cation bonds in which both neptunyl(V) ions act with respect to each other as lignads and as coordination centers simultaneously, forming dimeric An₂O₄²⁺ cations. In complexes I–III, each Np atom has the coordination polyhedron (CP) in the form of a pentagonal bipyramid with the “yl” O atoms in the apical positions; the neptunyl(V) groups are appreciably nonlinear. The equatorial plane of the bipyramids is constituted by two N atoms of phenanthroline, O atom of the other NpO₂⁺ cation, and two O atoms of the C₆H₅COO^- (I), o-C₆H₄FCOO^- (II), and p-C₆H₄FCOO^- (III) anions. The Np⋅⋅⋅Np interatomic distances in the dimetic NpO₂⁺ cations (Å) are 3.40519(17) (I), 3.43891(17) (II), and 3.4271(3) (III). The main differences in the structures of I–III are manifested in the conformational characteristics and are caused by the effect of C-H⋅⋅⋅O and C-H⋅⋅⋅F hydrogen bonding.