Ternary Complexes of BiI3/SbI3 with Thioalkane Ligands

Reactions of BiI3/CuI and SbI3/CuI produced a wide range of products when reacted with mono-, di, and trithioalkane ligands tetrahydrothiophene (THT), 1,3-dithiolane (DTL), and 1,4,7-trithiacyclononane (9S3). Reactions of BiI3/CuI mixtures with THT in toluene produce 2-D sheet networks BiCu3I6(THT)n (n = 2, 3, or 4), depending on reaction conditions. All three structures are based on BiI6 octahedra, which share pairs of (μ2-I)2 with Cu3(THT)n units. Reactions of SbI3/CuI with THT in toluene produced a SbCu3I6(THT)2 network that shows Cu3(μ2-THT)2 units, like its Bi congener, but Cu6(μ2-I)6 barrels rather than rhombs. A molecular compound, Sb3Cu3I12(THT)6 consists of a face-sharing Sb3I12 stack, in which the Cu-THT units are bonded in asymmetric fashion about the central SbI6. The reaction of BiI3/CuI with 9S3 produced the only ionic compound seen in this study. 9S3 adopts a crown shape to chelate Cu atoms in a tridentate fashion in both the cation and the anion, while the [Bi4CuI18(9S3)]5– anion features the common [Bi2I9]3– cluster. Reactions of BiI3/CuI and SbI3/CuI with DTL produce isostructural 1D linear chain networks consisting of pnictogen-iodine octahedra bound to three Cu atoms in an edge-sharing manner. Metal-halide bonds were investigated via QTAIM and NLMO analyses, demonstrating that these bonds are largely ionic and occur between the Bi/Sb and I p orbitals. Hirshfeld analysis shows significant H···H and H···I interactions. Diffuse reflectance spectroscopy (DRS) reveals band edges for the Bi species of 1.71–1.82 eV, while those for the neutral Sb complexes are in the range of 1.94–2.06 eV. Mapping of the electronic structure via density of state calculations indicates population of antibonding Bi/Sb–I orbitals in the excited state.