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=L-1-L-3 or Ph-2[14]aneP(2)S(2)) (L-1=Ph2P(CH2)(2)S(CH2)(2)S(CH2)(2)PPh2, L-2= Ph2P(CH2)(2)S(CH2)(3)S(CH2)(2)PPh2, L-3=Ph2P(CH2)(2)S(o-C6H4)S(CH2)(2)PPh2, Ph-2[14]aneP(2)S(2)=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. 6H(2)O with L (L=L-1-L-3) and NH4PF6 in EtOH solution to give a green/brown solid, followed by halogen oxidation of this product in CH2Cl2 solution using X-2/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(L-2)](2)[CoCl4]. 4H(2)O and [CoCl2(L-3)]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-ol form in the solid state and this is also consistent with the solution P-31{H-1} NMR spectroscopic data. Co-59 NMR spectroscopy reveals a very broad single resonance at approximate to 3200 ppm for these species. (C) 1999 Elsevier Science Ltd. All rights reserved.