Coordination complexes of the bismuth(iii) thiolates Bi(SC6F5)3 and Bi(SC6Cl5)3 with pyridineligands

Abstract

The chloro-aryl bismuth thiolate Bi(SC₆Cl₅)₃ has been prepared from the reaction between BiPh₃ and the thiol HSC₆Cl₅ by analogy with the previously described synthesis of the fluoro-aryl species Bi(SC₆F₅)₃. The compound Bi(SC₆Cl₅)₃ is only sparingly soluble but can be isolated as a dmf adduct [Bi(SC₆Cl₅)₃(dmf)₂] (dmf = N,N-dimethylformamide) which adopts a five-coordinate square-based pyramidal geometry in which the two dmf ligands lie in the basal plane with a mutually cis configuration. Treatment of either Bi(SC₆F₅)₃ or Bi(SC₆Cl₅)₃ with pyridine or 2,2′-bipyridyl ligands affords the coordination complexes fac-[Bi(SC₆F₅)₃(py)₃] (two crystalline polymorphs), fac-[Bi(SC₆Cl₅)₃(py)₃], fac-[Bi(SC₆F₅)₃(4-pic)₃] (4-pic = 4-picoline), [Bi(SC₆Cl₅)₃(4-pic)₂], [Bi(SC₆F₅)₃(bipy)] (bipy = 2,2′-bipyridyl), [Bi(SC₆Cl₅)₃(bipy)], [Bi₂(SC₆Cl₅)₆(2-pic)₃] (2-pic = 2-picoline) and [Bi(SC₆F₅)₃(4-pic)]. Five- and four-coordinate complexes adopt square-based pyramidal and equatorially vacant, trigonal bipyramidal (disphenoidal) geometries respectively, the former having the two ligands cis to each other in the basal plane. The compound [Bi₂(SC₆Cl₅)₆(2-pic)₃] contains both five- and four-coordinate mononuclear units. A salt with the formula [4-picH][(4-pic)₂H][Bi₃(SC₆F₅)₁₁] was also isolated in which the anion contains a central bismuth bonded to five thiolate ligands with a square-based pyramidal geometry. Two cis-basal thiolates act as bridging groups to two outer bismuth centres each of which is four-coordinate with the expected disphenoidal geometry in which the bridging thiolate is in an axial position. The structure of the dinuclear arylbismuth thiolate compound [Bi₂Ph₂(SC₆F₅)₄(4-pic)₂] is also described. Intramolecular conformations and intermolecular associations in all structures are dominated by π–π-interactions.