Syntheses, Structures, Properties, and Theoretical Studies of d10 Metal Complexes of Ethylenediamine

Four new tris(ethylenediamine)-chelated metal complexes [Zn(en)3]I2·0.5en (1), [Cd(en)3]Cl2·H2O (2), [Cd(en)3]Br2 (3), and [Hg(en)3]Cl2 (4) have been synthesized by solvothermal reactions. The complexes contain discrete [M(en)3]2+ (M = Zn, Cd, Hg) cations and halide anions. The Zn2+ and Cd2+ ions are six-coordinated by three ethylenediamine molecules to form octahedra, while the Hg2+ ion has a trigonal prism coordination geometry. These complexes all display fluorescent properties in the blue range, which are attributed to a ligand-to-metal charge-transfer mechanism according to molecular orbital calculations. The solid-state diffuse reflectance spectra show that 1–4 are wide band-gap semiconductors. IR and thermogravimetric analyses for 1–4 are also presented in this paper.