Iron(III) complex of 2-acetylpyrazine thiosemicarbazone: synthesis, spectral characterization, structural studies and antitumoral activity

Abstract

[Fe(HL)₂]Cl₃ · 1.5H₂O (1), where HL = C₇H₉N₅S, 2-acetylpyrazine thiosemicarbazone, was obtained and fully characterized. X-ray diffraction studies show that complex 1 crystallizes in monoclinic lattice, space group P2₁ /n, with a = 11.342(6), b = 12.547(6), c = 17.056(9) Å, β = 103.551(7)°, V = 2360(2) ų, Z = 2, M_r = 1159.46, D _Calcd = 1.632 g cm⁻³, μ(Mo-Kα) = 1.188 mm⁻¹, F(000) = 1184, the final R ₁ = 0.0955 and wR ₂ = 0.2626. The 2-acetylpyrazine thiosemicarbazone is a tridentate ligand and binds to the metal through the pyrazine nitrogen, the imine nitrogen and the sulfur in the neutral thione form yielding an octahedral geometry. The title iron complex showed significant antitumor activity against the Ec9706 human esophagus cancer cell line with an IC₅₀ value (10.50 µM) in a micromolar range similar to cisplatin.

Keywords:

• Thiosemicarbazone
• Iron complex
• Crystal structure
• Cytotoxic activity

Acknowledgment

This work was financially supported by the Foundation of Educational Department of Henan Province (No. 2007150012).