The Influence of the Amine Concentration onto Product Formation: Crystal Structures, Thermal Stability and Spectroscopic Properties of Two New Manganese Thiostannates Obtained under Solvothermal Conditions

Abstract

Abstract Two new thiostannates with Mn2+ ions were obtained under solvothermal conditions applying different amine concentrations. [Mn(C6H14N2)2(H2O)]2Sn2S6 (1) (C6H14N2 = 1,2-diaminocyclohexane, 1,2-dach) crystallizes in the monoclinic space group C2/c (with a = 23.7500(18), b = 15.5655(16), c = 12.1072(9) Å , β = 113.532(8)°, Z = 8). The second compound, [Mn(C6H14N2)2]- Sn2S6 ・2 C6H15N2 (2), crystallizes in the triclinic space group P¯1 with a = 7.3019(6), b = 11.1798(9), c = 13.2837(11) Å , α = 76.877(10), β = 74.719(9), γ = 82.972(10)°, Z = 1. Both structures feature [Sn2S6]4− anions acting as bidentate ligands and joining the octahedrally coordinated Mn2+ cations, but in 1 a molecular complex is formed, whereas in 2 a one-dimensional coordination polymer is observed. In 1 the Mn2+ cation has bonds to four N atoms of two 1,2-dach ligands, to one H2O molecule, and to one S atom of the [Sn2S6]4− anion. The [Sn2S6]4− anion is located on a center of inversion joining two symmetry related complexes. In 2 Mn2+ is surrounded by four N atoms of two 1,2-dach ligands and by two S atoms of two neighboring [Sn2S6]4− anions. In contrast to 1 a negatively charged coordination polymer is formed with [Sn2S6]4− anions acting as linkers and the Mn2+ centered complexes being the nodes. The co-crystallized 1,2-dach molecules are protonated, and they are located between the chains. The first compound was obtained from diluted aqueous solutions of 1,2-dach, and 2 crystallized from solutions containing < 25% H2O. In both compounds several short S···H distances indicate weak hydrogen bonding interactions. Compound 1 is stable up to 121 °C and 2 up to 220 °C. In the Raman spectra of 1 and 2 resonances which are typical for [Sn2S6]4− units could be observed. The band gaps are found to be 2.6 eV (477 nm) and 3.1 eV (400 nm) for 1 and 2, respectively.