Co(III) and Cr(III) complexes of diphosphadithia ligands and the crystal structure of [CoCl2(L3)]PF6·CH2Cl2 (L3=Ph2P(CH2)2S(o-C6H4)S(CH2)2PPh2)

[CrX3(thf)3] (X=Cl or Br) reacts with L (L=L1–L3 or Ph2[14]aneP2S2) (L1=Ph2P(CH2)2S(CH2)2S(CH2)2PPh2, L2=Ph2P(CH2)2S(CH2)3S(CH2)2PPh2, L3=Ph2P(CH2)2S(o-C6H4)S(CH2)2PPh2, Ph2[14]aneP2S2=4,8-diphenyl-1,11-dithia-4,8-diphosphacyclotetradecane) and TlPF6 in MeNO2 solution to yield the distorted octahedral complexes [CrX2(L)]PF6 as green coloured solids in high yield. UV/visible spectroscopy suggests that these are cis-dihalo species and they have also been characterised by IR spectroscopy, electrospray mass spectrometry and microanalyses. The Co(III) analogues [CoX2(L)]+ are readily prepared in a two-stage reaction, involving treatment of CoX2·6H2O with L (L=L1–L3) and NH4PF6 in EtOH solution to give a green/brown solid, followed by halogen oxidation of this product in CH2Cl2 solution using X2/CCl4, to give the final products as brown coloured solids. A mixture of PF6− and [CoX4]2− anions are present in the final Co(III) compounds in varying ratios. Crystal structures of [CoCl2(L2)]2[CoCl4]·4H2O and [CoCl2(L3)]PF6·CH2Cl2 confirm tetradentate P2S2 coordination of L in each case, with mutually cis halogens completing the distorted octahedral geometry. In both cases the complex cation adopts the cis-α form in the solid state and this is also consistent with the solution 31P{1H} NMR spectroscopic data. 59Co NMR spectroscopy reveals a very broad single resonance at ≈3200 ppm for these species