Formation of PbS materials from lead xanthate precursors

Abstract

Six lead xanthate adducts Pb(S₂COR)₂.L [R = Et, ⁿBu, L = bipy, TMEDA (tetramethylethylenediamine), PMDETA (pentamethyldiethylenetriamine)] have been synthesised and the structures of all, save Pb(S₂COBuⁿ)₂.TMEDA (4) which is an oil, determined. Pb(S₂COEt)₂.TMEDA (3) is seven-coordinate at lead through three chelating ligands and one weak intermolecular Pb‥S interaction. Both Pb(S₂COR)₂.bipy [R = Et (1), ⁿBu (2)] are dimers in which one xanthate is terminal and the other μ₂ bridging at each sulphur, generating an eight-coordinate lead when the bipy donor is included. Both Pb(S₂COR)₂.PMDETA [R = Et (5), ⁿBu (6)] are seven-coordinate at lead by virtue of two bidentate chelating xanthate ligands and a tridentate PMDETA; there are no intermolecular interactions. Trends in the ²⁰⁷Pb NMR chemical shifts mirror the changes in the intramolecular coordination number across the series. Pb(S₂COEt)₂.TMEDA (3) has been used to deposit PbS films on glass, Mo-coated glass and Si by AACVD. Pb(S₂COEt)₂ also generated PbS nanocubes when decomposed under an autogenerated pressure.