Dinuclear Zn(II) and Hg(II) complexes of an angular dipyridyl ligand: syntheses, crystal structures, and properties

摘要

The angular polytopic dipyridyl ligand 2,6-bis(quinoline-2-carboxamido)pyridine (H_2L) was prepared. Assemblies of H_2L with ZnAc_2 and HgAc_2 resulted in two new dinuclear complexes [Zn_2(L)(Ac)_2]?1.5H_2O?0.5CH,OH (1) and [Hg_2(L)(Ac)_2]?5H_2O? CH_3OH (2) where the doubly deprotonated L~(2-) bi-chelate as μ-kN,N': kN",N"', bridging the two metal centers (Ac = acetate). In 1, the two Zn(II) ions are also doubly bridged by two Ac ions in a μ-kO: kO' coordination, and thus each metal center adopts a distorted tetrahedral geometry. In 2, each Ac ion is only terminal to Hg(II), in a rare distorted triangular or T-shaped coordination geometry. Free H_2L, 1, and 2 emit interesting bluish-green fluorescence with strong intensities. Thermogravimetric analysis of 1 shows that the dinuclear structure of 1 is stable to 382°C.