Novel antimony sulfides: Synthesis and X-ray structural characterization of Sb₃S₅•N(C₃H₇)₄ and Sb₄S₇•N₂C₄H₈

Novel antimony sulfides have been synthesized using hydrothermal techniques and organic amines as structure directing agents. The structures of two of these have been solved using single-crystal X-ray diffraction data. One, Sb₃S₅•N(C₃H₇)₄ (SbStpa), forms light yellow blades, has a second harmonic signal 4 times that of quartz, and was synthesized in the presence of tetrapropylammonium hydroxide. The structure contains independent chains of antimony sulfide, infinite in the [100] direction, which are separated by [N(C₃H₇)]₄⁺ ions. These chains are comprised of edge-linked five-membered rings of SbS₃-pyramids. A second compound, Sb₄S₇•N₂C₄H₈ (SbSpip), crystallizes as red tablets in the presence of triethylenetetramine. The structure incorporates a breakdown product of the added amine, molecules of diprotonated piperazine, [N₂C₄H₈]²⁺. The organic is accommodated between slabs of [Sb₄S₇]^2-, infinite in the (010) plane. These slabs consist of chains containing three-membered rings of SbS₃-pyramids joined by individuald three-coordinated antimony sulfide moieties. Both structures crystallize in the space group Ama2 with a = 10.360 (2), b = 23.474 (3), c = 9.336 (1) Å for SbStpa and a = 9.9498 (9), b = 28.513 (4), and c = 5.9032 (8) Å for SbSpip.