Syntheses and Structures of Blue-Luminescent Mercury(II) Complexes with 2,6-Bis(imino)pyridyl Ligands

Seven five-coordinate 2,6-bis(imino)pyridyl mercury complexes, [2,6-(ArNCMe)2C5H3NHgCl2·nCH3CN] (Ar = C6H5, n = 1.5, 1; Ar = 2,6-iPr2C6H3, n = 0, 2; Ar = 2,6-Me2C6H3, n = 1, 3; Ar = 2-MeC6H4, n = 1, 4; Ar = 4-MeC6H4, n = 1, 5; Ar = 2,4,6-Me3C6H2, n = 1, 6; Ar = 2,6-Et2C6H3, n = 0, 7), were synthesized by reactions of the corresponding bis(imino)pyridine ligands with HgCl2 in CH3CN, and in good yield. The structures of complexes 1−6 were determined by single-crystal X-ray diffraction. In all complexes, the metal center is tridentately chelated by the ligand and further coordinated by two chlorine atoms, resulting in a distorted trigonal bipyramidal geometry. All complexes have blue luminescence at room temperature in solution and the solid state. At 293 K in a CH2Cl2 solution, the fluorescent emission maxima for complexes 1−7 are at λ = 395, 400, 407, 403, 427, 415, and 403 nm, respectively, which can be attributed to ligand-centered π* → π transitions.