Syntheses, studies and crystal structures of coordination polymers and dinuclear complexes of mercury(II) halides and thiocyanate with a symmetrical Schiff base ligand

A series of mercury(II) compounds, [Hg2(μ-L)(SCN)4]n (1), [Hg2(μ-L)(μ-Cl)2Cl2]n (2), [Hg2(μ-L)Br4].[Hg2(μ-L)(μ-Br)2Br2]n (3) and [Hg2(μ-L)I4] (4) {L = N,N′-(bis-(pyridin-2-yl)benzylidene)-1,2-ethanediamine} have been prepared and characterized by using microanalytical, spectroscopic, thermal and X-ray crystallographic results. In solid states 1 and 2 have 2D and 1D coordination polymer structure, respectively. Solid state 3 consists of both 1D coordination polymers and dinuclear units. Solid state 4 is only composed of dinuclear units. In the polymeric structures, each mercury(II) center is five coordinated with trigonal bipyramidal geometry in 1D and square pyramidal environment in 2D coordination polymers. Coordination geometry around Hg centers in dinuclear units is tetrahedral. HOMO and LUMO of the title compounds and also the energy gap among them have been studied by using the density functional theory (DFT/B3LYP) method with the LANL2DZ pseudo-potential.