Synthesis, reactivity and crystal structures of cobalt complexes [Co2(CO)2(µ-X)(µ-Y)(dppm)2](X = CO, S or SO2; Y = CO or SO2; dppm = Ph2PCH2PPh2)

Abstract

The reaction of SO₂ with the M–M bond of the cobalt(0) complex [Co₂(CO)₂(µ-CO)(dppm)₂]1[dppm = bis(diphenylphosphino)methane] results in the substitution of the bridging CO group by SO₂ and the addition of a second SO₂ group to give [Co₂(CO)₂(µ-SO₂)₂(dppm)₂]2. The reaction of 1 with thiirane, C₂H₄S, or CO gives the insertion products [Co₂(CO)₂(µ-CO)(µ-X)(dppm)₂](X = CO 3, or S 4). The X-ray molecular structure analysis of the sulfur-bridged dimer 4 shows the presence of a distorted A-frame skeleton. These crystals contain 1.5 molecules of acetone per asymmetric unit and are monoclinic, space group P2₁/n,a= 14.950(5), b= 25.480(5), c= 15.682(2)Å, β= 98.18(2)°, T= 200 K and Z= 2; final R= 0.074. The complexes 3 and 4 react with SO₂ by substitution to give the SO₂-bridged complexes [Co₂(CO)₂(µ-X)(µ-SO₂)(dppm)₂](X = CO 5, or S 6). The X-ray molecular structure analysis of [Co₂(CO)₂(µ-S)(µ-SO₂)(dppm)₂]6 shows the sulfur and sulfur dioxide ligands in symmetrically bridging position between both cobalt centres. The crystals are monoclinic, space group P2₁/n, a= 12.850(5), b= 27.660(4), c= 16.056(5)Å, β= 93.85(3)°, T= 205 K and Z= 4; final R= 0.063.