Chiral platinum(II) complexes. Crystal and molecular structures of cis-[PtPhCl((R,R)-CHIRAPHOS)] and cis-[PtCl2((R,R)-CHIRAPHOS)]

Phosphinic Platinum Complexes with 8-Thiotheophylline Derivatives: Synthesis, Characterization, and Antiproliferative Activity

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.

A Luminescent Platinum(II) 2,6-Bis(N-pyrazolyl)pyridine Complex

Four platinum(II) cationic complexes were prepared with the mer-coordinating tridentate ligands 2,6-bis(N-pyrazolyl)pyridine (bpp) and 2,6-bis(3,5-dimethyl-N-pyrazolyl)pyridine (bdmpp): [Pt(bpp)Cl]Cl.H(2)O; [Pt(bdmpp)Cl]Cl.H(2)O; [Pt(bpp)(Ph)](PF(6)); [Pt(bdmpp)(Ph)](PF(6)). The complexes were characterized by (1)H NMR spectroscopy, elemental analysis, and mass spectrometry, and the structures of the bpp derivatives were determined by X-ray crystallography. [Pt(bpp)Cl]Cl.2H(2)O: monoclinic, P2(1)/n, a = 11.3218(5) A, b = 6.7716(3) A, c = 20.6501(6) A, beta = 105.883(2) degrees, V = 1522.73(11) A(3), Z = 4. The square planar cations stack in a head-to-tail fashion to form a linear chain structure with alternating Pt...Pt distances of 3.39 and 3.41 A. [Pt(bpp)(Ph)](PF(6)).CH(3)CN: triclinic, P, a = 8.3620(3) A, b = 10.7185(4) A, c = 13.4273(5) A, alpha = 96.057(1) degrees, beta = 104.175(1) degrees, gamma = 110.046(1) degrees, V = 1072.16(7) A(3), Z = 2. Cyclic voltammograms indicate all four complexes undergo irreversible reductions between -1.0 and -1.3 V vs Ag/AgCl (0.1 M TBAPF(6)/CH(3)CN), attributable to ligand- and/or metal-centered processes. By comparison to related 2,2':6',2' '-terpyridine complexes, the electrochemical and UV-visible absorption data are consistent with bpp being both a weaker sigma-donor and pi-acceptor than terpyridine. Solid samples of [Pt(bpp)(Ph)](PF(6)) at 77 K exhibit a remarkably intense, narrow emission centered at 655 nm, whereas the other three complexes exhibit only very weak emission.