A theoretical study of uranyl hydroxide monomeric and dimeric complexes

Structures of uranyl hydroxide monomeric UO₂(OH)₂ ⁰, and dimeric (UO₂)₂(OH)₂ ²⁺ were studied by hybrid density functional theoretical calculations. It was found out that both the monomeric ortho-UO2(OH)20 and dimeric (UO₂)₂(OH)₂ ²⁺ complexes have bent O=U=O angles (~170°). This is attributed to significant donation from the equatorial OH⁻ ligands to the uranyl moiety. It was also found that the ortho- and meta-UO₂(OH)₂(H₂O)₃ ⁰ complexes lie very close in energy, and that both isomers may exist in normal aqueous media.