Monomeric, one- and two-dimensional networks incorporating (2,6-Me2C6H3S)2Pb building blocks

Abstract

The amine coordination of lead(II) has been examined through the preparation and structural analysis of Lewis base adducts of bis(thiolato)lead(II) complexes. Reaction of Pb(OAc)₂ with 2,6-dimethylbenzenethiol affords (2,6-Me₂C₆H₃S)₂Pb (6) in high yield. The solubility of 6 in organic solvents allows for the preparation of the 1∶2 Lewis acid–base adduct [(2,6-Me₂C₆H₃S)₂Pb(py)₂] (7), and 1∶1 adducts [(2,6-Me₂C₆H₃S)₂Pb(μ₂-bipy)]_∞ (8) and [(2,6-Me₂C₆H₃S)₂Pb(μ₂-pyr)]_∞ (9) (where py = pyridine, bipy = 4,4′-bipyridyl and pyr = pyrazine) from reaction with an excess of the appropriate amine. In contrast to 7, reaction of (C₆H₅S)₂Pb (1) with pyridine afforded the 2∶1 adduct [(C₆H₅S)₄Pb₂(py)]_∞ (10). Compounds were characterized via elemental analysis, FT-IR, solution ¹H and ¹³C{¹H} (6) NMR spectroscopy, and X-ray crystallography (7–10). The structures of 7–9 show the thiolate groups occupying two equatorial positions and two amine nitrogen atoms occupying axial coordination sites, yielding distorted see-saw coordination geometries, or distorted trigonal bipyramids if an equatorial lone pair on lead is considered. The absence of intermolecular contacts in 7 and 8 result in monomeric and one-dimensional polymeric structures, respectively. Weak Pb⋯S intermolecular contacts in 9 result in the formation of a two-dimensional macrostructure. In contrast, the structure of 10, shows extensive intermolecular Pb⋯S interactions, resulting in five- and six-coordinate bonding environments for lead(II), and a complex polymeric structure in the solid state. This demonstrates the ability of the 2,6-dimethylphenylthiolate ligand to limit intermolecular lead–sulfur interactions, while allowing the axial coordination of amine Lewis base ligands.