Mercury(II) halide adducts of an olefinic double betaine: [{Hg2L2X4·6HgX2}n] [X = Cl, Br; L = cis-(p-Me2NC5H4N)2C2(COO)2]

Two polymeric mercury(II) halide adducts of an olefinic double betaine, cis-(p-Me₂NC₅H₄N⁺)₂C₂(COO^?)₂ (L), have been prepared and characterized by X-ray crystallography. {Hg₂L₂Cl₄·6HgCl₂}_n] (1) crystallizes in the monoclinic space group C2/c with Z = 4, and {Hg₂L₂Br₄·HgBr₂}_n] (2) in the triclinic space group P with Z = 1. Complexes 1 and 2 are structurally similar, being composed of centrosymmetric fourteen-membered rings and nearly linear HgX₂ (X = Cl, Br) moieties that are further inter-linked by weak HgX HgCl = 2.930–3.136(9) Å, HgBr = 3.057–3.310(6) Å] and HgO 2.64, 2.75(3) Å] bonds to generate a two-dimensional polymeric network.