Exploring the scope of [Pt2(4-FC6H4)4(μ-SEt2)2] as a precursor for new organometallic platinum(II) and platinum(IV) antitumor agents

Abstract

The new compound [Pt2(4-FC6H4)4(μ-SEt2)2] (A) was prepared and fully characterized. The reactions of compound A with ligands ArCH=NCH2CH2NMe2 (Ar = 2-BrC6H4, 1a; 2,6-Cl2C6H3, 1b; 4-ClC6H4, 1c; 2-Cl,6-FC6H3, 1d) were studied under different conditions and produced platinum(II) compounds [Pt(4-FC6H4)2(ArCH=NCH2CH2NMe2)] (2b−2d), containing a bidentate [N,N′] ligand, as well as cyclometalated platinum(IV) or platinum(II) compounds such as [PtBr(4-FC6H4)2(C6H4CH=NCH2CH2NMe2)] (4a) or [PtCl{(3-FC6H3)(2-XC6H3)CH=NCH2CH2NMe2}] (5b: X = Cl; 5d: X = F), containing a tridentate [C,N,N′] ligand and either a five (4a) or a seven (5b, 5d) membered metallacycle. These compounds exhibit a great antiproliferative activity against non-small lung cancer cells (A549), and the best result was obtained for compound 2c (IC50 = 0.3 ± 0.1 μM). While compounds 5 alter the mobility of plasmid DNA in a similar way to cisplatin, compound 4 was less efficient in removing the supercoils from DNA. In spite of the very low IC50 value obtained for compound 2c, this compound does not interact with DNA, and it is neither an intercalator nor a topoisomerase I inhibitor.