Steric effects in complexes of diphenyl(2-pyridyl)phosphine oxide with the uranyl ion. Synthetic, structural and theoretical studies

The structure of a diphenyl(2-pyridyl)phosphine oxide uranyl nitrate compound shows a monodentate mode of bonding for the ligand through the phosphine oxide oxygen atom to the uranyl group. The pyridyl nitrogen atom is uncoordinated. Theoretical studies reveal that the 2:1 complex with two monodentate phosphine oxide ligands with uranyl nitrate is more stable than the corresponding 1:1 complex with one chelating bidentate phosphine oxide ligand by 13.5 kcal/mol.