Platinum metal complexes of mixed thia/oxa ionophores. The synthesis and single-crystal X-ray structures of [Pd([15]aneS2O3)2][PF6]2 and [RuCl(PPh3)([15]aneS2O3)2]PF6·H2O ([15]aneS2O3= 1,4,7-trioxa-10,13-dithiacyclopentadecane)

Abstract

The synthesis and characterisation of a series of mixed thia/oxa donor macrocyclic complexes cis-[MCl₂([15]aneS₂O₃)], [M([15]aneS₂O₃)₂]²⁺(M = Pd or Pt), [MCl₂([15]aneS₂O₃)₂]⁺(M = Rh or Ir), and [RuCl(PPh₃)([15]aneS₂O₃)₂]⁺([15]aneS₂O₃= 1,4,7-trioxa-10,13-dithiacyclopentadecane) are described. Reaction of MCl₂(M = Pd or Pt) with one molar equivalent of [15]aneS₂O₃ affords the complex cis-[MCl₂([15]aneS₂O₃)]; addition of a second equivalent affords the bis complex cations [M([15]aneS₂O₃)₂]²⁺. The complex [Pd([15]aneS₂O₃)₂][PF₆]₂ crystallises in the monoclinic space group P2₁/c, a= 10.394(4), b= 14.003(4), c= 11.675(5)Å, β= 104.22(3), U= 1 647 ų, and Z= 2. The single-crystal X-ray structure shows the Pd^II occupying a crystallographic inversion centre, with square-planar co-ordination by the [15]aneS₂O₃ ionophores through the thioether S-donors, Pd–S(1) 2.314 9(10), Pd–S(4) 2.301 7(10)Å. The O-donors point away from the Pd^II to give a relatively flattened complex. Reaction of MCl₃·3H₂O (M = Rh or Ir) with two molar equivalents of [15]aneS₂O₃ affords the complex cations [MCl₂([15]aneS₂O₃)₂]⁺. Treatment of [RuCl₂(PPh₃)₃] with two molar equivalents of [15]aneS₂O₃ gives the complex cation [RuCl(PPh₃)([15]aneS₂O₃)₂]⁺. The complex [RuCl(PPh₃)([15]aneS₂O₃)₂]PF₆·H₂O crystallises in the orthorhombic space group Pbcn, a= 19.252 6(14), b= 25.968(3), c= 18.903 3(23)Å, U= 9 451 ų, and Z= 8. The single-crystal X-ray structure shows octahedral co-ordination at Ru^II with the Cl^– and PPh₃ ligands mutually trans, Ru–Cl 2.458(3), Ru–P 2.319(3)Å. The [15]aneS₂O₃ ligands are bound exocyclically to Ru^IIvia four thioether S-donors, Ru–S 2.390(3), 2.394(3), 2.395(3), 2.405(3)Å. The O-donors of [15]aneS₂O₃ are not bound to the metal centre but, unlike the complex [Pd([15]aneS₂O₃)₂]²⁺, are directed towards the face occupied by the Cl^– ligand and away from the sterically bulky PPh₃ ligand. The [15]aneS₂O₃ ligands in [RuCl(PPh₃)([15]aneS₂O₃)₂]⁺ therefore form a cavity at one face of the metal centre in which the co-ordinated Cl^– ligand sits.