Syntheses, crystal structures, and properties of two new one-dimensional heterometallic selenides: [DBNH]4[M3Sn4Se11(Se2)2] (M = Cd, Hg)

Two new one-dimensional ternary selenides, [DBNH]4[M3Sn4Se11(Se2)2] (M = Cd (1), Hg (2); DBN = 1,5-diazabicyclo[4.3.0]non-5-ene), have been prepared under solvothermal conditions by the reactions of Sn, CdCl2/HgCl2, Se, DBN, and H2O at 160 °C for 6 days. Single crystal X-ray analyses reveal that compounds 1 and 2 are isostructural and crystallize in the monoclinic space group C2/c (for 1, a = 22.236(4) Å, b = 12.623(3) Å, c = 21.756(4) Å, β = 109.91(3)°; for 2, a = 22.137(4) Å, b = 12.663(3) Å, c = 21.780(4) Å, β = 109.48(3)°). Both compounds contain the similar wave-like ribbon (which is built up by SnSe4 tetrahedra, CdSe4/HgSe4 tetrahedra, and Se22− ions) and the protonated DBNH+ cations (which are located in the inter-ribbon spaces). A pseudo-3D network is formed through C–H⋅⋅⋅Se and N–H⋅⋅⋅Se hydrogen bonds with adjacent ribbons. The sharp UV-Vis absorption edges suggest band gaps of 2.13 eV for 1 and 2.18 eV for 2, respectively.