Synthesis and Characterization of Organotin(IV) N-Benzyl-N-Isopropyldithiocarbamate Compounds: Cytotoxic Assay on Human Hepatocarcinoma Cells (HepG2)

Problem statement: Several studies on organotin(IV) dithiocarbamate compounds have been carried out but not on the synthesis and characterization together with cytotoxic assay of organotin(IV) N-benzyl-N-isopropyldithiocarbamate compounds. Approach: Three new organotin(IV) compounds of type N-benzyl-N-isopropyldithiocarbamate have been successfully synthesized by direct reaction between secondary amine with organotin(IV) chloride using in situ method. All the compounds were characterized using elemental analysis, gravimetric analysis, infrared spectroscopy and Nuclear Magnetic Resonance (NMR) spectroscopy. Results: Elemental and gravimetric analyses data of these compounds showed that agreed with the predicted formula, (CH₃)₂Sn[S₂CN(C₇H₇)(i-C₃H₇)]₂ (1), (C₄H₉)₂Sn[S₂CN(C₇H₇)(i-C₃H7)]₂ (2) and (C₆H₅)₃Sn[S₂CN(C₇H₇)(i-C₃H₇)] (3). The infrared spectra of these compounds showed the thioureide bond, v(C=N) which occurred at 1438-1440 cm^-1 and the v(C=S) band appeared in the range of 967-973 cm^-1. The presence of the v(C=N) and v(C=S) bands in the infrared spectra confirmed the presence of dithiocarbamate ligand in that compounds. The bond between sulphur and tin atom were supported with the presence of peak in the range of 365-445 cm^-1 that known to be as stretching mode of v(Sn-S). The most important signal in the ¹³C NMR spectra was the chemical shift of NCS₂ group. The ¹³C NMR spectra of these compound showed a chemical shift in 195.06-202.65 ppm range, which is attributed to the carbon atom of NCS₂ group. The crystal structure of compound 2 (dibutyltin(IV) N-benzyl-N-isopropyldithiocarbamate) has been determined by X-ray single crystal analysis, which shows unsymmetrical nature of the ligand towards coordination to tin. It crystallizes in triclinic P1 space group with the crystal cell parameter: a = 17.7745 (2) (Å), b = 19.5463 (3) (Å), c = 26.2062 (4) (Å), α = 102.5254 (7)°, β = 95.1492 (7)°, γ= 110.2569 (8)°, Z = 10, V (ų) = 8202.1 (2) and R = 0.028. In addition, these compounds were screened for their cytotoxic activity on Human Hepatocarcinoma Cells (HepG2). Based on the cytotoxic activity, compounds 2 and 3 showed cytotoxic activity but compound 1 is inactive against HepG2 cells. Conclusion: The results of this study showed that the studied compounds might indeed be potential sources of anticancer agents and these would further enable us to evaluate their utility in biomedical field.