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 (A) 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.