Synthesis and cytostatic activity of Pt(II) complexes of intramolecularly coordinated phosphine and stibine ligands

The intramolecularly coordinated phosphine and stibine ligands L 1 PPh 2 ( 1 ), L 2 PPh 2 ( 2 ) and L 2 SbPh 2 ( 3 ) containing Y,C,Y‐chelating ligands, L 1  = 2,6‐( t BuOCH 2 ) 2 C 6 H 4 − and L 2  = 2,6‐(Me 2 NCH 2 ) 2 C 6 H 4 − , were prepared and characterized. The treatment of these ligands 1 , 2 , 3 with PtCl 2 yielded complexes trans ‐{[2,6‐( t BuOCH 2 ) 2 C 6 H 3 ]PPh 2 } 2 PtCl 2 (4), cis ‐{[2,6‐(Me 2 NCH 2 ) 2 C 6 H 3 ]PPh 2 }PtCl 2 (5), and cis ‐{[2,6‐(Me 2 NCH 2 ) 2 C 6 H 3 ]SbPh 2 }PtCl 2 (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 1 H, 13 C and 31 P 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‐(Me 2 NCH 2 ) 2 C 6 H 3 ]PPh 2 }PtI 2 ( 7 ) and {[2,6‐(Me 2 NCH 2 ) 2 C 6 H 3 ]SbPh 2 }PtI 2 ( 8 ), while the same reaction of 4 with NaI did not proceed. As the compounds 7 and 8 structurally resemble cisplatin, complex {{[2‐(Me 2 NCH 2 )‐6‐(Me 2 NHCH 2 )C 6 H 3 ]PPh 2 }PtCl 2 } + 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 (IC 50  = 27.6 ± 1.8 µmol l −1 ) and human promyelocytic leukemia HL‐60 (IC 50  = 55.9 ± 4.9 µmol l −1 ). Copyright © 2012 John Wiley & Sons, Ltd.