Five dimeric thiogermanates with transition metal complexes of multidentate chelating amines: Syntheses, structures, magnetism and photoluminescence

Five new thiogermanates, [NiII(dien)2]2(Ge2S6) (dien = diethylenetriamine) (1), [NiII(dien)2](H2pipe)(Ge2S6) (pipe = piperazine) (2), {[MnII(tren)]2(μ2-Ge2S6)} (tren = N,N,N-tris(2-aminoethyl)amine) (3) and {[MII(tepa)]2(μ2-Ge2S6)} (M = Mn (4a), Ni (4b); tepa = tetraethylenepentamine), have been obtained solvothermally in the presence of tri-(L3), tetra-(L4) and penta-dentate (L5) chelating amines and transition metal (TM) ions. Single-crystal X-ray diffraction analyses show that compounds 1–2 are comprised of discrete (Ge2S6)4− anions and TM complex (TMC) cations, while compounds 3–4b are composed of each dimeric (Ge2S6)4− anion bridging two TMC cations via TM–S bonds to form a neutral molecule. Notably, two interesting in situ metal/ligand reactions were observed in the solvothermal syntheses of 2 and 3. The present compounds exhibit wide optical gap ranging from 2.94 to 3.39 eV and photoluminescence with the emission maxima occurring around 440 (1, 2, 3 and 4b) and 489 nm (4a). Magnetic measurements show the presence of weak antiferromagnetic interactions between magnetic centers in the five compounds.