- Thermodynamic characteristics of thermal dissociation of platinum tetrachloride
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The pressure of thermal dissociation of platinum tetrachloride by the first step PtCl4(s) = PtCl3(s) + 0.5 Cl2(g) was measured by the static method with a quartz membrane-gauge zero-pressure manometer. An approximating equation for the dissociation pressure vs. temperature was found. The enthalpy (52160±880 J mol-1) and entropy (72.1±1.6 J mol-1 K-1) of dissociation were calculated. The heat of formation found for platinum tetrachloride (-246.3±1.3 kJ mol-1) at 298.15 K agrees well with the value obtained by the calorimetric method (-245.6±1.9 kJ mol-1).
- Semenova,Titov,Chusova
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- Thermodynamics of the Pt-Cl system
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Using a static method three individual compounds in system of Pt-Cl: PtCl4, PtCl3, and PtCl2 are shown to exist. PtCl was shown not to exist. The enthalpies of formation of platinum chlorides were measured by calorimetry by reduction of the compounds with gaseous hydrogen. The recommended values for the enthalpies of formation at 298.15 K are -137.7 ± 0.3, 194.2 ± 1.0, and 245.6 ± 1.9 kJ/mol for PtCl2(s), PtCl3(s) and PtCl4(s), respectively.
- Chusova, Tamara P.,Semenova, Zinaida I.
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- Outer-sphere electron transfer from platinum(II) to Keggin-type 12-tungstocobaltate(III) in the presence and absence of chloride ions
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The reaction between Pt(II) and [CoIIIW12I 40]5- proceeds with two, one-electron steps involving formation of unstable Pt(III) followed by its reaction with another oxidant. The reaction rate is unaffected by the [H+] as there are no protonation equlibria involved with both the reactants whereas, chloride ion accelerates the reaction and the reaction follows chloride independent and dependent paths leading to a two term rate law, rate= {k1 + Kk 2 [Cl-]} [Pt(II)] [CoIIIW12O 40]5-. The chloride ion dependent path is due to rapid substitution of chloride ion on PtCl42-. The products formed have been found to be PtCl4(aq) and PtC6 2- in the absence and presence of chloride ion respectively. Increase in the ionic strength and decrease in the relative permittivity of the medium increase the rate of the reaction. This is due to the formation of an outer-sphere complex between the two reactants. The activation parameters in the presence and absence of chloride ions have also been determined and the values support the proposed mechanism.
- Bhosale,Gokavi
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p. 799 - 802
(2007/10/03)
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- Structure and bonding of the hexameric platinum(II) dichloride, Pt6Cl12 (β-PtCl2)
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The crystal structure of Pt6Cl12 (β-PtCl2) was redetermined (R3m ah = 13.126 A, ch = 8.666 A, Z = 3; arh = 8.110 A, α = 108.04°; 367 hkl, R = 0.032). As has been shown earlier, the structure is in principle a hierarchical variant of the cubic structure type of tungsten (bcc), which atoms are replaced by the hexameric Pt6Cl12 molecules. Due to the 60° rotation of the cuboctahedral clusters about one of the trigonal axes, the symmetry is reduced from Im3m to R3m (I3m). The molecule Pt6Cl12 shows the (trigonally elongated) structure of the classic M6X12 cluster compounds with (distorted) square-planar PtCl4 fragments, however without metal-metal bonds. The Pt atoms are shifted outside the Cl12 cuboctahedron by Δ = +0.046 A (d(Pt-Cl) = 2.315 A; d(Pt-Pt) = 3.339 A). The scalar relativistic DFT calculations results in the full m3m symmetry for the optimized structure of the isolated molecule with d(Pt-Cl) = 2.381 A, d(Pt-Pt) = 3.468 A and Δ = +0.072 A. The electron distribution of the Pt-Pt antibonding HOMO exhibits an outwards-directed asymmetry perpendicular to the PtCl4 fragments, that plays the decisive role for the cluster packing in the crystal. A comparative study of the Electron Localization Function with the hypothetical trans-(Nb2Zr4)Cl12 molecule shows the distinct differences between Pt6Cl12 and clusters with metal-metal bonding. Due to the characteristic electronic structure, the crystal structure of Pt6Cl12 in space group R3m is an optimal one, which results from comparison with rhombohedral Zr6I12 and a cubic bcc arrangement.
- Von Schnering, Hans Georg,Chang, Jen-Hui,Peters, Karl,Peters, Eva-Maria,Wagner, Frank R.,Grin, Yuri,Thiele, Gerhard
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p. 516 - 522
(2008/10/08)
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- Anti-tumor platinum complexes
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Platinum complexes, having anti-tumor activity, which include at least one functional ketone group or aldehyde, optionally conjugated as a linkable hydrazone complex. The functional ketone and aldehyde groups and the functionalized hydrazone complexes are
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