First example of thiostannates with lanthanide-containing counter cations: Solvothermal synthesis, crystal structures and properties of thiostannates with neodymium(III) and gadolinium(III) complexes of bidentate and tridentate amino ligands

Three new lanthanide thiostannates [Ln2(en)6(μ2-OH)2]Sn2S6 (Ln = Nd (1), Gd (2); en = ethylenediamine) and [Gd(dien)3]2[(Sn2S6)Cl2] (3) (dien = diethylenetriamine) were first synthesized by treating LnCl3 with SnCl4 and S under mild solvothermal conditions. Compounds 1 and 2 are isostructural. They consist of a binuclear lanthanide(III) complex [Ln2(en)6(μ2-OH)2]4+ cation and a dimeric [Sn2S6]4− anion. The anion is built up by two SnS4 tetrahedra sharing a common edge. The Nd3+ and Gd3+ ions are in an eight-coordinated environment forming distorted bicapped trigonal prisms. Compound 3 is composed of two monouclear [Gd(dien)3]3+ complex cations, a [Sn2S6]4− anion, and two chlorine ions. The Gd3+ ion has a nine-coordinated environment forming a distorted tricapped trigonal prism. In compounds 1–3, extensive hydrogen bonds are formed leading to three-dimensional networks of anions and cations. The band gaps of 2.42 eV for 1 and 3.17 eV for 2 have been derived from optical absorption spectra. The new lanthanide compounds might be the precursors for ternary lanthanide thiostannates by the heat treatment under nitrogen atmosphere to get rid of organic components.