Sulphonation of palladium–carbon bonds: synthesis and X-ray crystal structures of the disulphinato derivatives [Pd{S(O)2CH2CH2CH2CH2S(O)2}(tmen)](tmen = Me2NCH2CH2NMe2) and [Pd{S(O)2Me}2(tmen)]

Abstract

The sulphonation of [P[graphic omitted]H₂)(tmen)](1a) and [PdMe₂(tmen)](1b)(tmen = Me₂NCH₂CH₂NMe₂) in CH₂Cl₂ leads to the corresponding disulphinato compounds [P[graphic omitted](O)₂}(tmen)](2a) and [Pd{S(O)₂Me}₂(tmen)](2b), while the reaction of (1a) and (1b) with liquid SO₂ gives the derivatives [P[graphic omitted]S(O)₂}(tmen)]·2SO₂(3a) and [Pd{S(O)₂Me}₂(tmen)]·2SO₂(3b) respectively. On heating under vacuum, (3a), and (3b) lose SO₂ and revert to the disulphinates (2a) and (2b), respectively, which give (3a) and (3b) on reaction with liquid SO₂. The X-ray crystal structures of complexes (2a) and (2b) have been determined: (2a), a= 9.259(8), b= 13.380(10), c= 6.213(5)Å, β= 92.96(2)°, space group P2₁, Z= 2, R= 0.0325 for 2 619 observed reflections; (2b), a= 9.377(2), c= 16.182(3)Å, space group P4₁2₁2, Z= 4, R= 0.0396 for 1 249 observed reflections. The absolute configurations of the two structures have been determined, and the conformations of the two molecules compared. The metal co-ordination in both compounds is square planar with a very small tetrahedral deformation: av. Pd–S 2.288(1) and av. Pd–N 2.168(4)Å. Closure of the P[graphic omitted] chelate ring in compound (2a) causes a small increase in the S–Pd–S angle which is 91.3(1)° in (2a) and 90.3(1)° in (2b), but does not significantly influence the co-ordination of the diamine [av. N–Pd–N 82.9(1)°]. The conformation of the palladadithiaheptane ring in (2a) is twisted-boat.