Dinuclear and polymeric Hg(II) complexes with 1-(2-furoyl)thiourea derivatives: Their crystal structure and related properties

Dimeric and polymeric complexes bis{[(1-(2-furoyl)-3-bencyl-3-phenylthiourea-κS)chloromercury(II)]-μ-chloro} (HgCl₂-FBFT) and catena-poly{[(1-(2-furoyl)-3-bencylthiourea-κS)chloromercury(II)]-μ-chloro} (HgCl₂-FBT) were prepared by reaction of HgCl₂ with 1-(2-furoyl)-3-bencyl-3-phenylthiourea (FBFT) and 1-(2-furoyl)-3-bencylthiourea (FBT) in ethanol. Their crystal structures were solved and refined from X-ray powder diffraction data using direct space global optimization strategy (simulated annealing) followed by the Rietveld refinement. Both solids exhibit 1:1 metal:ligand stoichiometry and a distorted tetrahedral geometry for the coordination mercury centers. The mercury(II) complexes were characterized by elemental analysis, Raman, NMR and TG-DTG data. Complex HgCl₂-FBFT crystallizes in the triclinic system, space group P1¯, while HgCl₂-FBT crystallizes in the orthorhombic system, space group Pcnn. In the dimeric complex HgCl₂-FBFT each Hg(II) atom is found coordinated to S atom of ligand, and to a terminal and two bridging chlorine atoms. Neighboring dimers remain together in the solid through dipolar and quadrupolar interactions. The complex HgCl₂-FBT is a polymer of mercury(II) bridged to two chlorine ions and also coordinated by terminal chlorine ion and a molecule of ligand through the S atom. This compound exhibits intramolecular and intermolecular hydrogen bonds; these last ones are responsible for packing of the polymeric chains in a 3D framework. The photoluminescence properties indicate that both complexes are fluorescent materials with maximum emission at 425 nm.