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

• Published in: Acta crystallographica. Section C, Structural chemistry Structural chemistry, 2021-07, Vol.77 (7), p.402-410
• Main Authors: Schwade, Vânia Denise, Tirloni, Bárbara
• Format: Article
• Language: English
• ISSN: 2053-2296; 2053-2296
• DOI: 10.1107/S2053229621006379

Pyrimidine-2-thione (HSpym) reacts with lead(II) thiocyanate and lead(II) bromide in N , N -dimethylformamide (DMF) to form poly[(μ-isothiocyanato-κ 2 N : S )(μ 4 -pyrimidine-2-thiolato-κ 6 N 1 , S : S : S : S , N 3 )lead(II)], [Pb(C 4 H 3 N 2 S)(NCS)] n or [Pb(Spym)(NCS)] n , (I), and the polymeric one-dimensional (1D) compound catena -poly[[μ 4 -bromido-di-μ-bromido-(μ-pyrimidine-2-thiolato-κ 3 N 1 , S : S )(μ-pyrimidine-2-thione-κ 3 N 1 , S : S )dilead(II)] N , N -dimethylformamide monosolvate], {[Pb 2 Br 3 (C 4 H 3 N 2 S)(C 4 H 4 N 2 S)]·C 3 H 7 NO} n or {[Pb 2 Br 3 (Spym)(HSpym)]·DMF} n , (II a ), respectively. Poly[μ 4 -bromido-di-μ 3 -bromido-(μ-pyrimidine-2-thiolato-κ 3 N 1 , S : S )(μ-pyrimidine-2-thione-κ 3 N 1 , S : S )dilead(II)], [Pb 2 Br 3 (C 4 H 3 N 2 S)(C 4 H 4 N 2 S)] n or [Pb 2 Br 3 (Spym)(HSpym)] n , (II b ), could be obtained as a mixture with (II a ) 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 (II a ). 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 (II a ) and its desolvated version (II b ) represent the first structurally characterized Pb II compounds containing neutral HSpym and anionic Spym − ligands. After a prolonged time in solution, (II a ) 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.