Ternary Complexes of BiI₃/CuI and SbI₃/CuI with Tetrahydrothiophene

Reactions of BiI3/CuI mixtures with tetrahydrothiophene (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 (mu(2)-I)(2) with Cu-3(THT)(n) units. BiCu3I6(THT)(2) features Cu-2(mu(2)-I)(2) rhombs with close Cu center dot center dot center dot Cu interactions and is accompanied by formation of the very complex HBi3Cu12I22(THT)(8). Reactions of SbI3/CuI with THT in toluene produced a SbCu3I6(THT)(2) network shows Cu-3(mu(2)-THT)(2) units, like its Bi congener, but Cu-6(mu(2)-I)(6) barrels rather than rhombs. Isolated SbI3 units are stacked above the Cu6I6 barrels. 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. 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 center dot center dot center dot H and H center dot center dot center dot 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.