- Crystalline O,O′-di-sec-butyl and O,O′-diethyl dithiophosphate platinum(II) complexes: Synthesis, 13C and 31P CP/MAS NMR, single crystal X-ray diffraction studies and thermal behaviour
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Crystalline bis(O,O′-di-sec-butyldithiophosphato)platinum(II) was prepared and studied by means of 13C, 31P CP/MAS NMR spectroscopy and single-crystal X-ray diffraction. The unit cell of the platinum(II) compound is comprised of one centrosymmetric mononuclear molecule [Pt{S2P(O-sec-C4H9)2}2], in which the dithiophosphate groups display structural equivalence in both 31P NMR and XRD data. A pair of the dithiophosphate ligands exhibit the same S,S′-bidentate chelating structural function and form two planar four-membered chelate rings, [PtS2P], in this molecule. The planar configuration of the [PtS4] chromophore in structure 1 is governed by the dsp2-hybrid state of platinum(II). The structural states of the dithiophosphate groups in two different samples of complex 1 (one crystallised from ethanol and the other one precipitated from an aqueous solution) are all characterised by almost rhombic 31P chemical shift tensors. The observed essential dispersion of the 31P NMR chemical shift is caused by a coexistence of six optical isomers of molecule 1. The thermal behaviour of this compound was studied by means of simultaneous thermal analysis (a combination of TG and DSC) under an argon atmosphere. The thermal behaviour shows that the mass of 1 is lost in three steps, involving successive thermal decompositions of the organic and inorganic parts of this compound with platinum(II) dithio-meta-phosphate and reduced metallic platinum as the intermediate and the final products, respectively.
- Rodina, Tatyana A.,Ivanov, Alexander V.,Gerasimenko, Andrey V.,Lutsenko, Irina A.,Ivanov, Maxim A.,Hanna, John V.,Antzutkin, Oleg N.,Sergienko, Valentin I.
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- Synthesis and characterization of liquid platinum compounds
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Liquid platinum complexes were obtained with a ligand with alkyl chains that attach to the coordination plane perpendicularly and herewith render a close packing of the molecules difficult for certain chain lengths. Bis(O,O'-dialkyldithiophosphato)platinum(II) complexes, Pt(C(x)dtp)2, where the alkyl chains are methyl (x = 1), ethyl (x = 2), propyl (x = 3), butyl (x = 4), pentyl (x = 5), hexyl (x = 6), heptyl (x = 7), dodecyl (x = 12), and octadecyl (x = 18), were investigated. The platinum compounds were synthesized via two routes: reaction of tetrachloroplatinate(II) with ammonium-O,O'-dialkyldithiophosphates or oxidative addition of (O,O'-dialkylthiophosphoryl)disulfides to tris(styrene)platinum(0). The melting temperatures as a function of the alkyl chain length show a minimum for the complex with pentyl groups. The complexes with pentyl and hexyl groups are liquid at room temperature, and the complexes with butyl and heptyl groups melt only slightly above room temperature. Depending on the complex, the low melting temperatures are induced by an unfavorable packing of the molecules in the solid state, reflected in a low melting enthalpy, or melting entropy. The molecular weights of the liquid complexes are between 700 and 800 and, therefore, extraordinarily high for liquid metal compounds. Depending on the alkyl groups, the complexes decompose at 172-241°C. Crystals of bis(O,O'-diethyldithiophosphato)platinum(II), Pt(C2dtp)2, are monoclinic, space group P21/n, a = 8.90, b = 8.70, c = 12.45 A?, α = γ = 90°, β = 100.89°, and Z = 4. (C) 2000 Elsevier Science S.A.
- Gianini, Michel,Caseri, Walter R.,Gramlich, Volker,Suter, Ulrich W.
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- Experimental and First-Principles NMR Analysis of Pt(II) Complexes with O,O′-Dialkyldithiophosphate Ligands
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Polycrystalline bis(dialkyldithiophosphato)Pt(II) complexes of the form [Pt{S2P(OR)2}2] (R = ethyl, iso-propyl, iso-butyl, sec-butyl or cyclo-hexyl group) were studied using solid-state 31P and 195Pt NMR spectroscopy, to determine the influence of R to the structure of the central chromophore. The measured anisotropic chemical shift (CS) parameters for 31P and 195Pt afford more detailed chemical and structural information, as compared to isotropic CS and J couplings alone. Advanced theoretical modeling at the hybrid DFT level, including both crystal lattice and the important relativistic spin-orbit effects qualitatively reproduced the measured CS tensors, supported the experimental analysis, and provided extensive orientational information. A particular correction model for the non-negligible lattice effects was adopted, allowing one to avoid a severe deterioration of the 195Pt anisotropic parameters due to the high requirements posed on the pseudopotential quality in such calculations. Though negligible differences were found between the 195Pt CS tensors with different substituents R, the 31P CS parameters differed significantly between the complexes, implying the potential to distinguish between them. The presented approach enables good resolution and a detailed analysis of heavy-element compounds by solid-state NMR, thus widening the understanding of such systems.
- Roukala, Juho,Orr, Simon T.,Hanna, John V.,Vaara, Juha,Ivanov, Alexander V.,Antzutkin, Oleg N.,Lantto, Perttu
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p. 8326 - 8338
(2016/11/09)
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- DITHIOPHOSPHATO-PLATINUM-COMPLEXES FOR THE TREATMENT OF CANCERS
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Complex of formulas: (I), (II) or (III): which are suitable for the treatment of tumors.
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Page/Page column 33
(2008/06/13)
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