AB-INITIO STUDY OF THE (SO2)(SO2-) DIMER - STRUCTURES INVOLVING A 2-ELECTRON S-O BOND

The structure of the (SO2)(2)(-) dimer involving one or two S-O bonds has been investigated by means of ab initio calculations at the PUMP4/6-31 + G* //UMP2/6-31 + G* level. Two minima with one S-O bond are found; their formation energies are in reasonable agreement with experimental data. Two bifurcated structures with two equal S-O bonds are characterized as transition states. They allow oxygen exchange in each of the S-O bound minima. The possible structure of the dimer is discussed in comparison with our previous results in which a S-S bound dimer was found.