Cation–Cation Interaction in the Np(V) Complex with Cyclobutanecarboxylic Acid Anions, Na[NpO2(cbc)2]

Abstract

The Np(V) complex Na[NpO₂(cbc)₂] was isolated in the crystalline form and studied by single crystal X-ray diffraction. The coordination surrounding of the Np(1) atom is a pentagonal bipyramid with the O atoms of the NpO₂ group in apical positions. The equatorial plane of the bipyramid is constituted by one O atom of the adjacent NpO₂ group and four O atoms of three C₄H₇COO_– anions. Cation–cation (CC) interaction (mutual coordination of linear \(\rm{NpO}_2^+\) dioxocations) observed in the structure leads to the formation of chains of \(\rm{NpO}_2^+\) cations. The bridging anions link the \(\rm{NpO}_2^+\) cations along the chains with the formation of infinite anionic chains \(\left[ {\rm{Np}{O_2}{{(cbc)}_2}} \right]_{\rm{n}}^{{\rm{n -}} }\) oriented along [001] in the crystal. The Na₊ cations arranged between the \(\left[ {\rm{Np}{O_2}{{(cbc)}_2}} \right]_{\rm{n}}^{{\rm{n -}} }\) anionic chains link them in the [010] direction. As a result, electrically neutral layers parallel to the (011) plane are formed in the crystal.