Synthesis, properties, and crystal structures of benzene-1,2-dithiolato complexes of thallium(I) and -(III)

The syntheses, molecular structures and properties of homoleptic 1,2-S2C6H4 complexes of thallium(I) and thallium(III) with four-coordinated metal centers are described. Anaerobic treatment of TlCl, TlNO3, or Tl2CO3 with solutions of sodium methanolate and 1,2-(HS)(2)C6H4 in methanol gave after metathesis with [NEt(4)]Br yellow solutions of [NEt(4)](2)[{Tl(1,2-(mu-S)(2)C6H4)}(2)] ([NEt(4)](2)1). Yellow single crystals were obtained from saturated acetone solutions at -10 degrees C and the crystal data for [NEt(4)](2)1 are monoclinic, P2(1)/c, with Z = 2, a = 7.440(1) Angstrom, b = 16.373(3) Angstrom, c = 13.201(2) Angstrom, and beta = 97.08(1)degrees. Complex 1(2-), the first structurally characterized homoleptic ionic thiolate complex of thallium(I), contains rectangular bipyramidal [TlS4Tl] cages with the four sulfur atoms defining the equatorial plane and the two thallium atoms in axial positions. The S2C6H4 fragments are almost coplanar with the S-4 plane. In the crystal lattice, nearly linear Tl ... Tl chains align along the a-axis (offset ca. 3.0 degrees) with the ligand planes parallel to the bc-plane. Within and between dimers short Tl ... Tl distances are observed (Tl ... Tl' within a dimeric unit, 3.5116(4) Angstrom; Tl ... Tl between dimeric units, 3.9371(3) Angstrom) with the distance between dimeric units being the shortest contact between anions-Tl ... S distances between dimeric units are longer than 5.8 Angstrom. Aerobic treatment of TlCl, TlNO3, or Tl2CO3 with solutions of sodium methanolate and 1,2-(HS)(2)C6H4 in methanol and metathesis with [NEt(4)]Br led to [NEt(4)][Tl(1,2-S2C6H4)(2)] ([NEt(4)]2). Yellow single crystals were obtained from saturated acetone solutions at 0 degrees C and the crystal data for [NEt(4)]2 are orthorhombic, Pnn2, with Z = 2, a = 11.449(2) Angstrom, b = 10.060(2) Angstrom, c = 9.950(2) Angstrom. Complex 2(-) is the first homoleptic four-coordinate thiolate of thallium(III) and contains the unusually short Tl-S distance of 2.469(4) Angstrom. In solution, ion pairing results in chemical and magnetic inequivalence of the S2C6H4 ligands. Although both preparations employ the reaction of thallium(I) salts with 1,2-(NaS)(2)C6H4 in a 1:2 stoichiometry, complex 1(2-) is probably not an intermediate to the formation of 2(-). Exposing anaerobically prepared solutions of 1(2-) to air results in a series of color changes in the solution over a 20 min period; however, 2(-) could not be observed by NMR spectroscopy.