[C3H10NO]2[Sb4S7]: Solvothermal syntheses, crystal structures and properties of the first thioantimonates containing aminoalcohols as structure directors

Using solvothermal conditions two new thioantimonates with composition [C3H10NO]2[Sb4S7] were obtained containing protonated 1-amino-2-propanol as the structure directing molecule. Both compounds have the same composition but the anionic [Sb4S7]2− part is significantly different. In (1) three trigonal [SbS3] pyramids are connected via common corners yielding a [Sb3S6] ring. These rings are connected by another [SbS3] unit thus building the one-dimensional [Sb4S7]2− chain. In (2) a two dimensional [Sb4S7]2− anionic network is formed by the interconnection of two trigonal pyramidal [SbS3] units and two [SbS4] moieties. A remarkable feature of the structure is a [Sb4S10] moiety composed of four edge sharing [SbS4] units. The layered anion contains a Sb10S10 ring and the inter-layer distance of about 7.8 Å is caused by the special arrangement of the two crystallographically distinct protonated 1-amino-2-propanol cations. Both compounds were prepared using the same amount of starting materials but at different reaction temperatures. Hence, the two compounds are another examples for the sensitivity of reaction parameters in solvothermal syntheses. The compounds are optical semiconductors with band gaps of 2.10 eV (1) and 2.21 eV (2). Thermal decomposition in an inert atmosphere leads to a collapse of the structures and Sb2S3 is formed as the reaction product.