“…6,9,10 Strong An=O bonding reduces the Lewis basicity of the axial oxygen, 11 but the equatorial ligands increase electron density at the An center, weakening the An=O bond 11,12 and promoting a range of NCIs. The interaction between the actinyl oxo and neighboring groups can be classified into various forms, including actinyl−cation (ACIs), 13,14 actinyl−hydrogen (AHIs), 15,16 actinyl−halogen (AXIs), 10,12 and actinyl−actinyl interactions (AAIs). 17 ACIs, AHIs, and AXIs are found in both hexa-and pentavalent species; however, AAIs are more common in pentavalent species.…”