Complexation of Zn(II), Cd(II) and Hg(II) with thiourea and selenourea: A ¹H, ¹³C, ¹⁵N, ⁷⁷Se and ¹¹³Cd solution and solid-state NMR study

Abstract

Zinc(II), cadmium(II) and mercury(II) complexes of thiourea (TU) and selenourea (SeU) of general formula M(TU)₂Cl₂ or M(SeU)₂Cl₂ have been prepared. The complexes were characterized by elemental analysis and NMR (¹H, ¹³C, ¹⁵N, ⁷⁷Se and ¹¹³Cd) spectroscopy. A low-frequency shift of the C=S resonance of thiones in ¹³C NMR and high-frequency shifts of N–H resonances in ¹H and ¹⁵N NMR are consistent with sulfur or selenium coordination to the metal ions. The Se nucleus in Cd(SeU)₂Cl₂ in ⁷⁷Se NMR is deshielded by 87 ppm on coordination, relative to the free ligand. In comparison, the analogous Zn(II) and Hg(II) complexes show deshielding by 33 and 50 ppm, respectively, indicating that the orbital overlap of Se with Cd is better. Principal components of ⁷⁷Se and ¹¹³Cd shielding tensors were determined from solid-state NMR data.

Keywords:

• Thiourea
• Selenourea
• Zn(II), Cd(II), Hg(II) complexes
• NMR
• CP MAS NMR

Acknowledgements

This work was supported by the KFUPM Research Committee (Project CY/NMR STUDY/277) and the Chemistry Department of the King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia.

Notes

Corresponding author. Email: [email protected]

Additional information

Notes on contributors

Mohammed I. M. Wazeer *

Corresponding author. Email: [email protected]