Assembly of novel organic-decorated quaternary TM–Hg–Sb–Q compounds (TM = Mn, Fe, Co; Q = S, Se) by the combination of three types of metal coordination geometries

Abstract

Four organic-decorated quaternary TM–Hg–Sb–Q compounds, namely, [Mn(phen)]₂HgSb₂S₆ (phen = 1,10-phenanthroline) (1) and isomorphic [TM(tren)]HgSb₂Se₅ (TM = Mn (2), Fe (3), Co (4); tren = tris(2-aminoethyl)amine) have been solvothermally prepared, and structurally characterized by single crystal X-ray diffraction analyses. 1 and 2 (3, 4) feature distinct one-dimensional neutral infinite ribbon-like structures constructed by the combination of Sb³⁺, Hg²⁺ and TM²⁺, the latter two of which adopt different coordination modes. In compound 1, organic-decorated {[Mn(phen)]₂Sb₂S₆} clusters assembled by {MnS₄N₂} octhedra and {SbS₃} pyramids are bridged by the {HgS₂} groups in a linear fashion. Differently, the {SbSe₃} pyramids, {HgSe₄} tetrahedra and {TMSeN₄} trigonal-bipyramids in 2 (3, 4) are combined to form novel {[TM(tren)]₂Hg₂Sb₄Se₁₂} clusters, which are interconnected to form {[TM(tren)]HgSb₂Se₅}_n ribbons. The results of optical diffuse-reflectance measurements and band structure calculations based on DFT methods indicate that 1 and 2 (3, 4) are indirect and direct semiconductors, respectively. Photocatalytic experiments have shown the ability of 2 in photodegradation of Rhodamine B (RhB).