Solvothermal syntheses and characterizations of the first example of lanthanide selenidostannates prepared in mixed ethylene polyamines

Samarium selenidostannates [Hen][Sm(dien)3]Sn2Se6 (1), [Sm(trien)(tren)(Cl)]2Sn2Se6·0.5en (2), and [{Sm(en)(trien)}2(μ-OH)2]Sn2Se6 (3) (en = ethylenediamine, dien = diethylenetriamine, trien = triethylenetetramine, tren = tris(2-aminoethyl)amine) were prepared by solvothermal methods in mixed solvents of en/dien and en/trien, respectively. Compounds 1 and 2 consist of [Sn2Se6]4− anion and mononuclear Sm(III)-complex cations, and/or a protonated en and half a free en molecule. Compound 3 is composed of a [Sn2Se6]4− anion and a binuclear [{Sm(en)(trien)}2(μ-OH)2]4+ complex cation. As far as we know, 1–3 are the first examples of the lanthanide selenidostannates prepared in mixed ethylene polyamines. In the crystal structures of 1–3, the cations and anions are connected into three-dimensional supramolecular networks by N–H⋯Se and/or N–H⋯N, N–H⋯Cl and O–H⋯Se hydrogen bonds. Compounds 1–3 exhibit bandgaps in the range of 2.18–2.41 eV, and a distinct blue-shift of the bandgap from 2 to 1 and 3 is observed.