Coordination complexes of the bismuth(III) thiolates Bi(SC6F5)3 and Bi(SC6Cl5)3 with pyridine ligands

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 2,2ʹ-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 = 2,2ʹbipyridyl), [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 (pi)-(pi)-interactions.