Synthesis and cytostatic activity of Pt(II) complexes of intramolecularly coordinated phosphine and stibine ligands
Abstract
The intramolecularly coordinated phosphine and stibine ligands L1PPh2 (1), L2PPh2 (2) and L2SbPh2 (3) containing Y,C,Y-chelating ligands, L1 = 2,6-(tBuOCH2)2C6H4− and L2 = 2,6-(Me2NCH2)2C6H4−, were prepared and characterized. The treatment of these ligands 1, 2, 3 with PtCl2 yielded complexes trans-{[2,6-(tBuOCH2)2C6H3]PPh2}2PtCl2 (4), cis-{[2,6-(Me2NCH2)2C6H3]PPh2}PtCl2 (5), and cis-{[2,6-(Me2NCH2)2C6H3]SbPh2}PtCl2 (6) as the result of different ability of the starting compounds 1, 2, 3 to complex platinum centre.
Compounds 1, 2, 3, 4, 5, 6 were characterized by 1H, 13C and 31P NMR spectroscopy and electrospray ionization mass spectrometry, and molecular structures of 3, 4, 5, 6 were determined by X-ray diffraction analysis. The substitution reactions of complexes 4, 5, 6 were also studied.
The reaction of 5 and 6 with NaI yielded complexes {[2,6-(Me2NCH2)2C6H3]PPh2}PtI2 (7) and {[2,6-(Me2NCH2)2C6H3]SbPh2}PtI2 (8), while the same reaction of 4 with NaI did not proceed. As the compounds 7 and 8 structurally resemble cisplatin, complex {{[2-(Me2NCH2)-6-(Me2NHCH2)C6H3]PPh2}PtCl2}+Cl− (9) was prepared as water-soluble platinum complex.
The cytotoxic effect of complex 9 was evaluated on human T-lymphocytic leukemia cells MOLT-4 (IC50 = 27.6 ± 1.8 µmol l−1) and human promyelocytic leukemia HL-60 (IC50 = 55.9 ± 4.9 µmol l−1).