Ligands enhanced the AcAc triple bond

Abstract

The multiple bonds between actinide atoms and their derivatives are computationally investigated extensively and compounds with an unsupported actinide–actinide bond, especially in low oxidation states, have attracted great attention. Herein, high level relativistic quantum chemical methods are used to probe the Ac–Ac bonding in compounds with a general formula LAcAcL (L = AsH₃, PH₃, NH₃, H, CO, NO) at both scalar and spin–orbit coupling relativistic levels. H₃AsAcAcAsH₃, H₃PAcAcPH₃ and OCAcAcCO compounds show a type of zero valence AcAc triple bond with a 1σ²_g1π⁴_u configuration, and H₃AsAcAcAsH₃ has been found to have the shortest Ac–Ac bond length of 3.012 Å reported so far. The Ac₂ unit is very sensitive to the σ donor ligands and can form triple, double and even single bonds when suitable ligands are introduced, up to 3.652 Å with an Ac–Ac single bond in H₃NAcAcNH₃.