Three monomeric compounds containing the dipyrimidine-2-thiolategold(I) anion

One- and two-dimensional PbII compounds resulting from reaction of PbBr2 and Pb(SCN)2 with pyrimidine-2-thione

Pyrimidine-2-thione (HSpym) reacts with lead(II) thiocyanate and lead(II) bromide in N,N-dimethylformamide (DMF) to form poly[(μ-isothiocyanato-κ²N:S)(μ₄-pyrimidine-2-thiolato-κ⁶N¹,S:S:S:S,N³)lead(II)], [Pb(C₄H₃N₂S)(NCS)]_n or [Pb(Spym)(NCS)]_n, (I), and the polymeric one-dimensional (1D) compound catena-poly[[μ₄-bromido-di-μ-bromido-(μ-pyrimidine-2-thiolato-κ³N¹,S:S)(μ-pyrimidine-2-thione-κ³N¹,S:S)dilead(II)] N,N-dimethylformamide monosolvate], {[Pb₂Br₃(C₄H₃N₂S)(C₄H₄N₂S)]·C₃H₇NO}_n or {[Pb₂Br₃(Spym)(HSpym)]·DMF}_n, (IIa), respectively. Poly[μ₄-bromido-di-μ₃-bromido-(μ-pyrimidine-2-thiolato-κ³N¹,S:S)(μ-pyrimidine-2-thione-κ³N¹,S:S)dilead(II)], [Pb₂Br₃(C₄H₃N₂S)(C₄H₄N₂S)]_n or [Pb₂Br₃(Spym)(HSpym)]_n, (IIb), could be obtained as a mixture with (IIa) when using a lesser amount of solvent. In the crystal structures of the pseudohalide/halide Pb^II stable compounds, coordination of anionic and neutral HSpym has been observed. Both Spym^- (in the thiolate tautomeric form) and NCS^- ligands were responsible for the two-dimensional (2D) arrangement in (I). The Br^- ligands establish the 1D polymeric arrangement in (IIa). Eight-coordinated metal centres have been observed in both compounds, when considering the Pb...S and Pb...Br interactions. Both compounds were characterized by FT-IR and diffuse reflectance spectroscopies, as well as by powder X-ray diffraction. Compound (IIa) and its desolvated version (IIb) represent the first structurally characterized Pb^II compounds containing neutral HSpym and anionic Spym^- ligands. After a prolonged time in solution, (IIa) is converted to another compound due to complete deprotonation of HSpym. The structural characterization of (I) and (II) suggests HSpym as a good candidate for the removal of Pb^II ions from solutions containing thiocyanate or bromide ions.