Abstract
We studied the structure and bonding of uranyl carboxylic complexes by B3LYP hybrid density functional theory calculations． The geometry of uranyl oxalate 1:3 complex was discussed in terms of relative energy difference among the isomers． It was found out that there are several isomers that lie close in energy． The complexation of uranyl ion with formic and acetic acid was interpreted as the interaction of the HOMO (highest occupied molecular orbital) of carboxylic acid and the LUMO (lowest unoccupied molecular orbital) of uranyl ion． Consequently, uranyl formate favors monodentate coordination while the acetate favors bidentate coordination．
