A theoretical study of uranyl hydroxide monomeric and dimeric complexes

Structures of uranyl hydroxide monomeric UO2(OH)20, and dimeric (UO2)2(OH)22+ 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)22+ complexes have bent OUO angles (∼170°). This is attributed to significant π donation from the equatorial OH− ligands to the uranyl moiety. It was also found that the ortho- and meta-UO2(OH)2(H2O)30 complexes lie very close in energy, and that both isomers may exist in normal aqueous media.