Synthesis, structure and cytotoxicity studies on diorganotin (R = Me, Et) complexes of N-methylpyridoxine (MePN, PN = Vitamin B6) containing different anions

The interaction of dimethyl- and diethyltin(IV) cations with methylpyridoxine iodide ([MePN]I; PN = pyridoxine) was studied in ethanol/water (80:20(v/v) containing Cl−, NO3− or I− ions in different molar ratios. Several compounds containing the deprotonated (MePN-H) or neutral (MePN) ligand were isolated and characterized by elemental analysis, IR and NMR (1H, 13C, 119Sn) spectroscopy and FAB mass spectrometry. The compounds [SnMe2(MePN-H)](I3), [SnEt2(MePN-H)](I3), [SnMe2(MePN-H)(NO3)], [SnEt2(MePN-H)(NO3)] and [SnMe2(MePN)2]I2 were studied by X-ray diffractometry. The compounds in which the MePN-H ligand is present can be described as containing dinuclear [SnR2(MePN-H)]22+ (R = Me, Et) units, in which two bridging chelating methylpyridoxinato ligands link two metal atoms. Interactions also exist between the metal and the I3− or NO3− anions and these interactions differ in degree and type. On the other hand, in the only example of a complex containing the MePN ligand, the mononuclear [SnMe2(MePN)2]2+ unit is present. The in vitro antitumor activity of these complexes against the HeLa, A2780 and A2780cis cell lines was determined and compared with that of the equivalent PN derivatives.