Synthesis, structures and redox properties of platinum metal phosphathia complexes: Crystal structures of cis-[RuCl₂(RSC₂H₄SR)]·0.75Et ₂O and cis-[RhCl₂(RSC₂H₄RS)]PF ₆·CH₂Cl₂ (R = Ph₂PCH₂CH₂)

Reaction of [RuCl₂(py)₄] (py = pyridine) with 1 molar equivalent of the new tetradentate acyclic phosphathia compound RSC₂H₄SR (Ph₂PCH₂CH₂SCH₂CH ₂SCH₂CH₂PPh₂) or the macrocycle meso-Ph₂[14]aneP₂S₂ (4,8-diphenyl-1,11-dithia-4,18-diphosphacyclotetradecane) in refluxing toluene under a nitrogen atmosphere afforded the ruthenium(II) complexes [RuCl₂(RSC₂H₄SR)] and [RuCl₂(Ph₂[14]aneP₂S₂)] respectively as yellow solids. The crystal structure of [RuCl₂(RSC₂H₄SR)]·0.75Et₂O shows RSC₂H₄SR co-ordinated via all four donor atoms with the two P-donors occupying mutually trans co-ordination sites at Ru^II, and cis-dichlorides completing the overall octahedral stereochemistry, Ru-S 2.294(1), 2.292(1), Ru-P 2.339(2), 2.335(2), Ru-Cl2.463(1), 2.463(1) Å. Phosphorus-31 NMR spectroscopic studies on the macrocyclic species [RuCl₂(Ph₂[14]aneP₂S₂)] are consistent with a cis-dichloro isomer in which one Cl is trans to P and the other trans to S. Cyclic voltammetry showed a reversible one-electron oxidation occurring at E_1/2 = +0.16 and +0.32 V vs. ferrocene-ferrocenium for [RuCl₂(RSC₂H₄SR)] and [RuCl₂(Ph₂[14]aneP₂S₂)] respectively. The complexes [MCl₂(RSC₂H₄SR)]PF₆ (M = Rh or Ir) have also been prepared. The structure of [RhCl₂(RSC₂H₄SR)]PF₆·CH ₂Cl₂ shows discrete [RhCl₂(RSC₂H₄SR)]⁺ cations adopting a very similar arrangement to that in the ruthenium(II) analogue, with Rh-P 2.352(2), 2.342(2), Rh-S 2.303(2), 2.297(2), Rh-Cl 2.370(2), 2.359(2) Å. Rhodium-103 NMR spectroscopy reveals a triplet at δ + 1405 (J_RhP 85 Hz).