New μ-SnTe₄ and μ-Sn₂Te₆ ligands to transition metal: Solvothermal syntheses and characterizations of zinc tellurostannates containing polyamine ligands

Zinc tellurostannates [(Zn(teta))₂(μ-1κ:2κ-SnTe₄)] (1), [(Zn(teta))₃(μ₃-1κ:2κ:3κ-SnTe₄)]I₂ (2), [(Zn(tren))₂(μ-1κ:2κ-Sn₂Te₆)] (3), and [Zn(dien)₂]₄(Sn₂Te₆)_1.75(Sn₂Te₈)_0.25·dien (4) were prepared by the reactions of Zn, Sn, and Te with iodine ion assistant in teta and dien. The tetrahedral [SnTe₄]⁴⁻ anion coordinates to two [Zn(teta)]²⁺ units as a bidentate μ-1κ:2κ-SnTe₄ ligand to form the neutral complex 1. It coordinates to three [Zn(teta)]²⁺ units with a tridentate μ₃-1κ:2κ:3κ coordination modes, generating a complex cation [(Zn(teta))₃(μ₃-1κ:2κ:3κ- SnTe₄)]²⁺ in 2. In 3, the [Sn₂Te₆]⁴⁻ anion joins two [Zn(tren)]²⁺cations with the trans terminal Te atoms, forming neutral complex 3. The μ-1κ:2κ-SnTe₄, μ₃-1κ:2κ:3κ-SnTe₄, and μ-1κ:2κ-Sn₂Te₆ ligands to TM centers in 1–3 have not been observed before. Compound 4 contains a normal [Sn₂Te₆]⁴⁻ and an abnormal [(Sn₂Te₆)_0.75(Sn₂Te₈)_0.25]⁴⁻ anions. Compounds 1–4 exhibit narrow band gaps in the range of 1.47–1.98 eV, and a distinct red-shift of the band gaps is observed from 4 to 1−3. - Graphical abstract: Zinc tellurostannates were prepared with iodine ion assistant in polyamines, and first μ-1κ:2κ-SnTe₄, μ₃-1κ:2κ:3κ-SnTe₄, and μ-1κ:2κ-Sn₂Te₆ ligands TM centers were obtained. - Highlights: • Zinc-tellurostannates were first prepared with iodine ion assistant. • Novel μ-1κ:2κ-SnTe₄, μ₃-1κ:2κ:3κ-SnTe₄, and μ-1κ:2κ-Sn₂Te₆ ligands were obtained. • The Zinc tellurostannates exhibit optical bandgaps between 1.47 and 1.98 eV