Halide effects on formation and physicochemical properties of mercury(II) complexes containing Y-type tridentate N-donor

Self-assembly of HgX₂ (X^- = Cl^-, Br^-, and I^-) with Y-type 2,6-bis[(2-isonicotinoyloxy-5-methylphenyl)methyl]-1-isonicotinoyloxy-4-methylbenzene (L) yields 2D consisting of alternate prismatic P- and M-helical-linked-layers, 1D consisting of P- and M-helices, and simple 2D sheet in a unique Y-type mode, respectively. The L/Hg(II) ratio of each product (3/3 for Cl^-; 2/3 for Br^-; 1/3 for I^-) is dependent on the nature of the halide anions. The coordinating environments around of Hg(II) ion approximate to a square pyramid for Cl^-, a square planar and a distorted tetrahedral geometry for Br^-, and distorted tetrahedral arrangement for I^-, respectively. Photoluminescence wavelengths are strongly depending on the halide anions, and coordination ability to L is in the order of X^- = Cl^- > Br^- > I^-. Such physicochemical properties were explained by electronic and steric natures of halide anions.