Synthesis, crystal structures, and NMR (¹H, ¹³C) spectroscopy of Pd^II/Hg^II complexes with N, S-donor thiosemicarbazone/heterocyclic-2-thione ligands

Abstract

The reaction of 2-benzoylpyridine thiosemicarbazone, {(C₆H₅)(py-N¹)C²=N²-N³H-C¹(=S)-N⁴H₂, bzpytscH}, with palladium(II) chloride in acetonitrile yielded a heteroleptic complex, [Pd(N¹,N²,S-bzpytsc)Cl] (1), in which the thio-ligand coordinated through pyridyl nitrogen (N¹), azomethine nitrogen (N²) and sulfur as terdentate anion (N,N,S-bzpytsc^–). In another reaction, pyrimidine-2-thione (pymtH) with mercury(II) chloride in CH₃CN-DMF mixture formed a homoleptic compound, [Hg(N,S-pymt)₂] (2), similar to the literature report of formation of a homoleptic compound, [Hg(κ¹S-pyt)₂], from HgCl₂ and pytH in CH₃CN-DMF. A reaction of mercury(II) bromide with pyridine-2-thione (pytH) in CH₃CN-DMF mixture did not remove the bromides and rather yielded a heteroleptic complex of composition, [HgBr₂(κ¹S-pytH)₂] (3). NMR (¹H, ¹³C NMR) spectroscopy and infrared spectroscopy of 1–4 as well as crystal structures of 1, 3, and 4 are reported.

KEYWORDS:

• Palladium(II)
• thiosemicarbazone
• pyridine-2-thione
• mercury(II)
• pyrimidine-2-thione

Acknowledgment

The author thanks the Guru Nanak Dev University for Honorary Professorship to Dr. Tarlok Singh Lobana, while S. Virdi and R. Dhiman thank the Department of Chemistry for their research facilities. The authors thank Isabel Garcia-Santos of Universidad de Santiago, Spain for instrumental assistance. Funding for this research (to RJB) was provided by the National Science Foundation, Directorate for Mathematical and Physical Sciences (Grant No. CHE-1039027).

Disclosure statement

No potential conflict of interest was reported by the authors.