Quantum-chemical interpretation of cation-cation interactions

A mechanism of cation-cation (C-C) interaction of five-valent actinoids, AnO2+ (An=U, Np, Pu, Am) with some active cations, UO22+, Fe3+, In3+ in particular, is proposed. The interaction of UO22+ with UO2+ proceeding due to overlapping of filled molecular orbitals of UO2+ with empty UO22+ orbitals and vice versa is considered. The quantitative characteristic of the C-C interaction is the energy gap between the donor and acceptor orbitals. NpO22+ and PuO22+ interact with AnO2+ weaker than UO22+. The C-C interaction occurs if an unfilled acceptor orbital in one system is below the donor orbital energy level in another system and the acceptor orbital, as to its character, is mostly an orbital of the central atom