Synthesis and solid-state structural characterization of N,N′-dicyclohexyldithiooxamide complexes of HgX2(X = SCN or Cl)

Abstract

N,N′-Dicyclohexyldithiooxamide (H₂L) reacted with HgX₂(X = SCN or Cl) to form the novel mercury mixed-ligand complexes [Hg(H₂L)(SCN)₂]1, [HgCl₂(H₂L)]2 and [{HgCl₂(H₂L)}₂]·EtOH 3. The crystal and molecular structures of 1 and 3 have been determined. Crystals of 1 are monoclinic, space group P2₁/n(no. 14), with a= 11.318(1), b= 17.727(2), c= 11.536(2)Å, β= 109.08(2)° and Z= 4. Crystals of 3 are monoclinic, space group P2₁(no. 4), with a= 8.563(1), b= 21.414(3), c= 11.649(2)Å, β= 103.58(2)° and Z= 2. The structures were each refined by a full-matrix least-squares procedure to R1 = 0.031 for 2218 reflections with F² 2.0σ(F²) for 1 and R1 = 0.047 (2374 reflections) for 3. Complex 1 is mononuclear with HgS₄ units linked by short intermolecular S ⋯ S interactions. Complex 3 is a binuclear zwitterionic system with one S,S′-chelating H₂L ligand bonded to a mercury atom and a second ligand acting in an unusual' conformation as a S,S′-bidentate bridging group between the ionic species HgS₂Cl⁺ and HgCl₃^–. The two mercury atoms are separated at a non-interacting distance. The infrared spectra of the complexes in the range 650–200 cm^–1 are discussed in the light of the known structures.