Platinate , hydrate

Coste F, Malinge J-M, Serre L, Shepard W, Roth M, Leng M, Zelwer C. Crystal structure of a double-stranded DNA containing a cisplatin interstrand crosslink at 1.63°A resolution hydration at the platinated site. Nucleic Acids Res 1999 27 1837-1184. 

The thermodynamically stable form of bulk platinum in oxygen saturated water at ambient conditions is the completely hydrated platinum(IV)oxide, Pt02 4H20, also referred to as platinic acid H2Pt(OH) 14yl5) with a standard Gibbs energy of formation of -84 kJ mol" The formation of this compound will be even more favoured in the case of incompletely coordinated platinum. 

Complex platinous derivatives containing hydrazine are easily prepared by acting upon dichloro-diammino-platinum with hydrazine hydrate in absence of water. The addition of alcohol precipitates diammino-dihydrazino-platinous chloride in colourless prismatic... 

Dichloro - tetrammino - platinic Sulphate, [Pt(NH3)4Cl2JS04, separates as a white crystalline powder when sulphuric acid is added to a warm aqueous solution of the nitrate. If the solution be kept cool a hydrated salt separates in small needles. The salt is sparingly soluble in water, and silver nitrate does not remove chlorine from a cold aqueous solution. 

Dinitrato - tetrammino - platinic Chloride, [Pt(NH3)4(N03)2] C12.H20, is prepared by treating a boiling solution of hydroxo-nitrato-tetrammino-platinic nitrate, [Pt(NH3)4(0H)(N03)](N03)2, with hydrochloric acid. It separates as a white crystalline powder which may be reerystallised from water in large rhombic crystals. It is soluble in cold water, and loses water of hydration on heating to 100° C. Chlorine is completely precipitated by silver nitrate it therefore differs in this respect from the nitrate of dichloro-tetrammino-platinic series, with which it is isomeric. 

In view of the fact that the Fong s experiments involved repeated platinization of the surfaces of the platinum and Chi a layers (74,75), the observed photoreactivity may arise from a photocatalytic effect of the composite of Chi a hydrates and platinum rather than Chi a hydrates themselves. In this respect, it has been reported that Pt dispersions catalize dye-sensitized photoreduction of water (77,78). 

S. Koefed prepared apple-green crystals of platinous diamminonitritoehloro-nitrosylbydrochloride, Pt(NH3)2(N02)G.N0.HCl.fH20, by heating platinous tetramminodiehloride with sodium nitrite and dil. hydrochloric acid on a water-bath, and drying the product at 100°. The constitution of the salt without water of hydration, is represented ... 

Pt(NH30)(NH3)(N02)(0H)], and forms a monohydrate with alkali-lye, which, with hydrochloric acid, reforms the chloronitrite. Both the hydrate, and the nitritodihydroxylaminoammine with pyridine form platinous nitritopyridino hydroxylaminoanunine, [Pt(NH20)(Py)(NH3)(N02)], which is decomposed by acids. Similarly platinous trans-dinitritohydroxylamine, [PtfNHgO.HNH )-(N02)2], or... 

Deposition of platinum metal In the case of platinum no solid product was found. The ionic liquid darkened more and faster the smaller the distance between the surface of the ionic liquid [EMIM][TfO] containing tetrabutylammonium hexachloro-platinate ([n-Bu4N]2[PtCl6]) and the Ar/H2-plasma (3 1, overall pressure 100 Pa) was chosen. So far no other ionic liquid has been tested. The rate constant for the reduction of the tetrabutylammonium ion with a hydrated electron is only 1.4 x 106 LmoH1 s 1, hence the main rival pathway for reduction of platinum(IV) is the reduction of the imidazolium ion of the ionic liquid. As in the case of copper, a suitable platinum salt - maybe made by electro-oxidation of metallic platinum in a suitable ionic liquid - has to be found. 

Amberger 6 has used lanolin as protective colloid. The lanolin is impregnated with an aqueous solution of a platinous salt, and intimately mixed with the requisite quantity of alkali hydroxide to precipitate out the platinum as hydrated oxide. This is reduced to colloidal metallic platinum by hydrazine hydrate. Both the lanolin and the colloidal metal are dissolved by light petroleum or chloroform, and the whole of the metal with a portion of the lanolin may be reprecipitated on addition of alcohol—a reaction affording a means of increasing the concentration of the metal in the preparation. 

Platinum dichloride also results, mixed with a little tetrachloride, when platinum sponge or, better, platinum black, obtained by reduction of ammonium chlor-platinate by hydrogen gas at 100° C., is heated in chlorine to 360° C. It is obtained in a more pure condition by heating chlor-platinous acid, HaPtCl or the hydrated acid chloride, namely, trichlor-platinous acid, PtCl2.HC1.2H20 or H2PtCl3(0H)H20, to 100° C.7... 

In dilute solution the pure acid results on decomposing the barium or silver salt with the requisite amount of sulphuric or hydrochloric acid. The solution cannot be concentrated, however, without decomposition, hydrogen chloride being evolved. When evaporated in vacuo, a residue of hydrated acid dichloride or trichlor-hydroxy-platinous acid is left, namely, PtCL. HC1.2HaO or H2PtCl3(OH). HaO. If the evaporation is continued at 100° C. platinous chloride results. 

Trichlor-hydroxy-platinous Acid, H2PtCl3(OH).—The hydrate of this add, namely, H2PtCl3(0H).H20, is obtained as a reddish brown... 

Platinum Tetrachloride, Platinic Chloride, PtCl4.—This salt was first prepared in a hydrated form by Norton,5 who, however, failed to isolate the anhydrous salt. This latter may be obtained by heating partially dehydrated chlor-platinic acid in a current of chlorine at 360° C.6 The possibility of preparing it in this way has been disputed,7 but Gutbier, who carried out a number of experiments with chlor-platinic acid under a variety of conditions, was able to prepare the salt quite easily. In the neighbourhood of 60° C. the crystals melt in their... 

Hydrates of Platinum Tetrachloride.—Platinic chloride combines with water to yield a series of hydrates. The odahydrate, PtCl4. 8H20, crystallises from aqueous solutions of the salt in the form of red needles.3... 

The solubilities of the alkali brom-platinates in water and dilute hydrobromie acid decrease with increasing atomic weight of the alkali metal. The solutions obtained are red in colour, but turn yellow on dilution with water. Hydrazine hydrate decomposes them with ease, metallic platinum being deposited and nitrogen evolved. 

Hydrated Platinum Monoxide, Pt0.2H20, is obtained in a more or less impure condition by the addition of warm potassium hydroxide solution to platinous chloride.4 The pure hydrated oxide, however, may be obtained8 by boiling a solution of potassium chlor-platinite with the calculated amount of sodium hydroxide solution. The hydrated oxide separates out as a dark precipitate, which is readily oxidised by exposure to air, so that it is necessary to wash and dry it in an atmosphere of carbon dioxide. It retains its combined water very tenaciously, and cannot be completely dehydrated without partial decomposition. 

Ehrsson, H.C., Wallin, I.B., Andersson, A.S. and Edlund, P.O. (1995) Cisplatin, trans-platin, and their hydrated complexes separation and identification using porous graphitic carbon and electrospray ionisation mass spectrometry. Anal. Chem., 67, 3608-11. 

A vacuum pump, with an intervening trap, is connected to the flask, and the hydrochloric acid solution is evaporated to dryness by placing the flask in a pan of hot water. The product is a crude form of hydrated hexachloroplatinic(IY) acid strong heating must be avoided to prevent decomposition of the solid acid. The solid acid is redissolved in a minimal volume (approximately 10 ml.) of distilled water, and disodium hexachloro-platinate(IV) is precipitated by adding a threefold excess (8.0 g.) of solid sodium chloride to the solution and cooling the mixture in an ice-water bath. J... 

There are some serious drawbacks to the use of cis-platin in anticancer therapy. Severe toxicity problems occur, such as failure of the kidneys and bone marrow (nephrotoxicity and hematoxicity), nausea, intractable vomiting (emesis), peripheral neuropathy, deafness (ototoxicity), and seizures. These toxic side effects of cisplatin limit the dose that can be administered to patients typical doses are 100 mg day for up to five consecutive days. The nephrotoxicity can be reduced by hydration and diuresis. 5-HT3-receptor blockers control nausea and emesis. Much effort has been devoted to the development of chemopro-tective agents, which alleviate the side effects on normal tissues without compromising antitumor activity - mainly sulfur-containing agents such as sodium dithiocarbamate (Naddtc), 2-mercaptoethanesulphonate (mesna), and amifos-tine (WR-2721). Amifostine has recently been approved for coadministration with cisplatin, which reduces nephro- and neurotoxicity. ... 

Binary rhodium(lV) compounds are confined to the purple red tetrafluoride and the black dioxide. The hydrated dioxide may be prepared by oxidizing rhodium(IIl) compounds, either with chlorine or electrochemically. Attempts to dehydrate this material lead to decomposition. No cationic rhodium(IV) complexes have been characterized unambiguously, but both [RhCle] -and [RhFe] are well established. The alkali metal salts of the hexafluororhodate(lV) ion are all isomorphous with their platinate(fV) analogs. 

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