Two Novel Thioantimonates(III) with the Same Stoichiometric Sb:S Ratio but Different Crystal Structures: Solvothermal Synthesis, Crystal Structures, Thermal Stability and Spectroscopy of (C6N3H17)Sb6S10 and (C7N2H13)3Sb9S15

Abstract

AbstractThe two novel thioantimonates(III) (C6N3H172+)Sb6S10 (I) and (C7N2H13+)3Sb9S15 (II) were synthesized under solvothermal conditions reacting Sb and S with the amines 1‐(2‐aminoethyl)‐piperazine (C6N3H15) and 1, 5‐diazabicyclo[4.3.0.]non‐5‐en (DBN, C7N2H12), respectively. The compounds crystallize as red needles in the monoclinic non‐centrosymmetric space group P21 (I) and in the monoclinic space group P21/c (II) with lattice parameters a = 6.120(4) Å, b = 17.759(1) Å, c = 11.478(7) Å, β = 90.70(7)° for I and a = 10.2643(6) Å, b = 23.648(2) Å, c = 20.4655(11) Å, β = 104.430(7)° for II.In both compounds the primary building units (PBUs) are trigonal SbS3 pyramids and SbS4 moieties. The interconnection of these PBUs leads to the formation of six‐membered rings Sb3S3 and Sb3S4 semi‐cubes in I which are joined via common S atoms to form the one‐dimensional [Sb6S10]2‐ anion being directed along [001]. Neighbored chains are arranged in a way that pockets are formed which host the organic cations. The ammonium groups of the organic molecules are oriented towards the anion ensuring optimal S···H bonding interactions. Taking into account the longer Sb‐S bonds above 3Å a three‐dimensional network is formed with large cages containing the organic cations. In compound II the SbS3 pyramids and the SbS4 units each form individual chains by vertex linking. The central chain is exclusively formed by SbS4 units whereas the other two chains are composed of SbS3 pyramids. The interconnection of the chains via common corners yields the one‐dimensional [Sb9S15]3‐ multiple chain anion. Due to the connection mode Sb4S4 rings are formed which are condensed along [001]. The chains are stacked along [100] with an inter‐chain separation of about 7Å. In the [010] direction the anions are lined‐up with the shortest distance between neighbored anions of about 3.4Å. With the long Sb‐S distances layers within the (100) plane are formed. At elevated temperatures both compounds decompose via an internal redox reaction into Sb2S3 (Stibnite) and Sb. The optical band gaps of about 2 eV indicate that both compounds are semiconductors.