Monomeric and tetrameric mercury(II) complexes with iodo and N2O2/N3O ligands: Structure and blue luminescence

Abstract

The reaction of mercury(II) iodide and potential tetradentate ligand N-(2-pyridylmethyl)iminodiethanol (H2pmide) or N,N-bis(2-pyridylmethyl)-2-aminoethanol (bpaeOH) leads to the isolation of monomeric complex [Hg(H2pmide)(I)2] (1) and tetrameric {[Hg2(bpaeOH)2][Hg2I7]I} (2). The crystal structures of 1 and 2 have been characterized by single crystal X-ray crystallography. In mononuclear neutral complex 1, the Hg(II) ion is bonded with one H2pmide species and two iodide anions as a distorted square pyramidal structure. 2 is a tetranuclear neutral complex that is composed of two [Hg(bpaeOH)]2+ cations and one [Hg2I7]3− anion as well as additional I− anion. The [Hg2I7]3− species connected to both the [Hg(bpaeOH)]2+ and [Hg(bpaeOH)(I)]+ units on the opposite side, which gives rise to the tetranuclear structure. 1 shows strong fluorescent emission at 412 nm with a blue color in methanol solution, while 2 displays very weak emission at 467 nm in the solid state. Particularly, in the case of 1, quantum yield is ca. 8.1% and fluorescence decay lifetime is ca. 1.95 ns.