Formation and Characterization of the Uranyl-SO2 Complex, UO2(CH3SO2)(SO2)-

The uranyl-SO2 adduct, UO2(CH3SO2)(SO2)(-), was prepared and characterized by mass spectrometric studies as well as by density functional theory. Collision induced dissociation of UO2(CH3SO2)(2)(-) in an ion trap resulted in the formation of UO2(CH3SO2)(SO2)(-), which spontaneously reacted with O-2 to give UO2(CH3SO2)(O-2)(-), with SO2 released. The UO2(CH3SO2)(SO2)(-) complex is computed to have a triplet ground state at the B3LYP level, and the SO2 ligand is coordinated to uranium through two oxygen atoms, similar to the coordination mode of SO2 in its complexes with hard metals. On the basis of the calculated geometric parameters and vibrational frequencies of the SO2 ligand, the UO2(CH3SO2)(SO2)- complex can be considered as a (UO2+)-O-v cation coordinated by SO2- and CH3SO2- anions. The UO2(CH3SO2)(O-2)(-) complex is computed to have a peroxo ligand, suggesting that U-v in UO2(CH3SO2)(SO2)(-) is oxidized to the U-vi state upon O-2 substitution for SO2.