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Complexes [Pt(mu-N,S-8-TT)(PPh(3))(2)](2) (1), [Pt(mu-S,N-8-TT)(PTA)(2)](2) (2), [Pt(8-TTH)(terpy)]BF(4) (3), cis-[PtCl(8-MTT)(PPh(3))(2)] (4), cis-[Pt(8-MTT)(2)(PPh(3))(2)] (5), cis-[Pt(8-MTT)(8-TTH)(PPh(3))(2)] (6), cis-[PtCl(8-MTT)(PTA)(2)] (7), cis-[Pt(8-MTT)(2)(PTA)(2)] (8), and trans-[Pt(8-MTT)(2)(py)(2)] (9) (8-TTH(2) = 8-thiotheophylline; 8-MTTH = 8-(methylthio)theophylline; PTA = 1,3,5-triaza-7-phosphaadamantane) are presented and studied by IR and multinuclear ((1)H, (31)P[(1)H]) NMR spectroscopy. The solid-state structure of 4 and 9 has been authenticated by X-ray crystallography. Growth inhibition of the cancer cells T2 and SKOV3 induced by the above new thiopurine platinum complexes has been investigated. The activity shown by complexes 4 and 9 was comparable with cisplatin on T2. Remarkably, 4 and 9 displayed also a valuable activity on cisplatin-resistant SKOV3 cancer cells.

Treatment of [PtC12(Ph2PCH2PPh2-P,P')] with an excess of NaOH in NH3 at -50°C gives, in >80% yield, the cis and trans isomers of [(Ph2MeP)(Ph2PO)Pt(p-NH2)2Pt(POPh2)(PMePh2)J, the structure of the trans form being confirmed by X-ray crystallography; both the structure and the proposed mechanism display highly novel features.

The platinum mixed-phosphine complexes (SP-4,2)-[PtCl(8-MTT)(PPh3)(PTA)] (2) and cis-[Pt(8-MTT)2(PPh3)(PTA)] (3) (MTTH2 = 8-(methylthio)theophylline, PTA = 1,3,5-triaza-7-phosphaadamantane) have been prepared from the precursor cis-[PtCl2(PPh3)(PTA)] (1), which has been fully characterized by X-ray diffraction determination. Antiproliferative activity tests indicated that the presence of one lipophilic PPh3 and one hydrophilic PTA makes 1-3 more active than the analogues bearing two PPh3 or two PTA. The reactivity of cis-[PtCl2(PPh3)2], cis-[PtCl2(PTA)2], and cis-[PtCl2(PPh3)(PTA)] with the bis(thiopurines) bis(S-8-thiotheophylline)methane (MBTTH2), 1,2-bis(S-8-thiotheophylline)ethane (EBTTH2), and 1,3-bis(S-8-thiotheophylline)propane (PBTTH2) has also been investigated. New binuclear complexes have been prepared and identified by spectroscopic techniques and their antiproliferative activities on T2 and SKOV3 cell lines evaluated.

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A complete protocol for the synthesis of new palladacyclopentadienyl complexes with purine-based carbenes as supporting ligands is described. The new organometallic compounds were exhaustively characterized using NMR and infrared spectroscopies and elemental analysis. The single-crystal X-ray structure of complex 2b coordinating also a triphenylphosphine was resolved. Some of these complexes showed an antiproliferative activity comparable to or better than that of cisplatin on two human ovarian cancer lines: A2780 (cisplatin-sensitive) and A2780cis (cisplatin-resistant). Moreover, for complexes 2 and 3 (coordinating one purine-based N-heterocyclic carbene ligand and one phosphine) the cytotoxicity is associated with an evident induction of apoptosis. Finally, complexes 3, bearing one purine-based N-heterocyclic carbene ligand and one 1,3,5-triaza-7-phosphaadamantane, proved practically inactive on non-tumour fibroblast cells (MRC-5).KEYWORDS antiproliferative and pro-apoptotic activity, N-heterocyclic carbenes, ovarian cancer, palladacyclopentadienyl complexes, purine bases

The new water-soluble ruthenium(II) mononuclear complexes [RuCp(X)(PTA)(L)] (X = 8-thio-theophyllinate (TTH(-)), L = PTA (1), L = PPh(3) (7)); (X = 8-methylthio-theophyllinate (8-MTT(-)), L = PTA (2), L = PPh(3) (8)), (X = 8-benzylthio-theophyllinate (8-BzTT(-)), L = PTA (3), L = PPh(3) (9)) and binuclear complexes [{RuCp(PTA)(L)}(2)-μ-(Y-κN7,N'7)] (Y = bis(S-8-thiotheophyllinate)methane (MBTT(2-)), L = PTA (4), L = PPh(3) (10)), (Y = 1,2-bis(S-8-thiotheophyllinate)ethane (EBTT(2-)), L = PTA (5), L = PPh(3) (11)), (Y = 1,3-bis(S-8-thiotheophyllinate)propane (PBTT(2-)); L = PTA (6), L = PPh(3) (12)) have been synthesized and characterized by NMR, IR spectroscopy and elemental analysis. The single crystal X-ray structure of [RuCp(8-MTT-κS)(PTA)(2)] (2) was also obtained. The antiproliferative activity of the complexes on cisplatin-sensitive T2 and cisplatin-resistant SKOV3 cell lines has been evaluated.

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