Preparation of ruthenium silanethiolato complexes and their reactions with sulfur dioxide; possible models for the activation of SO2 in the homogeneously catalyzed Claus reaction

CpRu(PPh3)2SSiiPr3 (6a) was prepared by reacting [CpRu(PPh3)2(acetone)]BF4 and NaSSiiPr3. Complex 6a is substitution-labile and readily gave the mixed-ligand derivatives CpRu(PPh3)(L)SSiiPr3, where L=CO (6b), PMe3 (6c), P(OMe)3 (6d), upon treatment with the corresponding ligands. CpRu(dppe)SSiiPr3 (6e) was obtained from complex 6a and dppe via the intermediate formation of CpRu(PPh3)(η1-dppe)SSiiPr3. Treatment of complex 6a with one equivalent of SO2 gave primarily unstable CpRu(PPh3)(SO2)SSiiPr3 (6f). However, complexes 6b–e inserted one equivalent of SO2 solely at their SSiiPr3 function to give the unstable O-silyl thiosulfito complexes CpRu(PPh3)(L)SS(O)OSiiPr3 (L=CO (8b), PMe3 (8c), P(OMe)3 (8d)) as well as CpRu(dppe)SS(O)OSiiPr3 (8e). The SH bonds of CpRu(PPh3)2SH (7a) and CpRu(dppe)SH (7b) added to PhNSO to give CpRu(PPh3)2SS(O)NHPh (9a) and CpRu(dppe)SS(O)NHPh (9b), respectively. The crystal structure of complex 6a was determined. Crystallographic data for 6a: triclinic, P1̄, a=10.642(6) Å, b=11.068(8) Å, c=21.994(10) Å, α=79.27(5)°, β=89.22(5)°, γ=62.32(4)°, V=2246(2) Å3, Z=2.