PLATINUM COMPOUND

The procedure for the preparation of the platinum compounds is an extension of the method described by Kharasch and Ashford.5 A glacial acetic acid solution of chloroplatinic acid is mixed with the appropriate olefin, and in the ensuing reaction the platinum is reduced from the 4+ oxidation state to the 2 + state. The overall stoichiometry of these reactions is not known however, the reduction of the platinum is1 accompanied by the partial oxidation of the olefin. 

In a 125-ml. Erlenmeyer flask 5.0 g. (8.41 mmoles) of hydrated chloroplatinic acid is dissolved in 15 ml. of glacial acetic acid and the solution heated to 75°. Six milliliters of 1,5-cyclo-octadienej is added to the warm solution and the mixture swirled gently, cooled to room temperature, and diluted with 50 ml. of water. The black suspension is stored for one hour at room temperature, and the crude product is collected on a Buchner funnel, washed with 50 ml. of water, and finally 100 ml. of ether. The crude product is suspended in 400 ml. of methylene chloride 

A small amount of product can be recovered by evaporation of the methylene chloride-petroleum ether filtrate. The product can be recrystallized to yield white macroscopic crystals by dissolving the white powder in 150 ml. of boiling methylene chloride and evaporating the solution until crystallization commences. 

Dichloro(l,5-cyclooctadiene)platinum(II) is a white, air-stable solid. The compound is slightly soluble in solvents such as chloroform, acetic acid, sulfolane (tetrahydrothiophene 1,1-dioxide), and nitromethane. It decomposes slowly upon dissolution in dimethyl sulfoxide. The p.m.r. spectrum of the compound in chloroform shows resonances at 4.38r, /pt H = 65 Hz., for the olefinic protons and 7.29-r for the methylene protons. The infrared spectrum in Nujol has strong absorption maxima at 1334, 1179, 1009, 871, 834, and 782 cm.-1. 

A mixture of 5.0 g. (8.41 mmoles) of hydrated chloroplatinic acid and 6.2 g. (60 mmoles) of sodium bromide suspended in 15 ml. of glacial acetic acid in a 125-ml. Erlenmeyer flask is heated at 75° for 10 minutes. Six milliliters of 1,5-cycloocta-diene is added to the hot solution yielding a brown solution and a black precipitate containing the impure product. The pure product is isolated in exactly the same manner as that described for the preparation of dichloro(l,5-cyclooctadiene)-platinum(II). The clarified methylene chloride solution is very pale yellow. The yield of the very pale yellow product in the form of a finely divided powder was 3.22 g. (83%). Anal. Calcd. for C8H12PtBr2 C, 20.75 H, 2.61. Found C, 21.21 H, 2.66. 

Platinum slurries, obtained by potassium reduction of [P(C2H5)3]2PtX2 in ethereal solvents, exhibit similar reactivities with aryl halides to those of palladium. The yields of products are, as in the case of palladium, varied with the highest being for the more reactive aryl halides. The compounds possess the trans geometry as determined by NMR spectroscopy [14] and in contrast to the palladium compounds exhibit no photosensitivity. 

Highly reactive slurries of palladium and platinum have been prepared by alkali metal reduction of compounds [P(C2H5)3]2MX2 in ethers using simple 

Metal slurries prepared in the presence of triethylphosphine contain, besides the black insoluble metal powder, compounds of the metals in low oxidation states, most likely the known tri- and tetrakis phosphine metal compounds which are known to react with organic halides, and contribute to the yields of the products obtained here. 

Highly reactive transition metal powders have been prepared in the absence of stabilizing ligands. The ability to prepare these metals with simple apparatus is of great importance not only to synthetic organic, organometallic, and inorganic chemistry but also to catalysis and surface chemistry. 

11 Typical quantities are PdCh (1.22 g), EtaP (1.63 g), and K (0.53 g) and were mixed with 25 ml of THF. The mixture was refluxed for 20 h yielding the black metal slurry. The slurry was cooled to -78°C and CeFjBr (1.7g) was added. After 1 h, the reaction was warmed up to room temperature and worked up. Yields are based upon PdC.  

7 Mossbauer-Active Transition Metals Other than Iron 

The relatively small percentage resonance effects require measuring times on the order of 1 week. A representative Pt (99 keV) Mossbauer spectrum, that of Pt02 taken at 4.2 K [332], is shown in Fig. 7.71. 

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Pt—Q—Salt, [Pt(NH3)2(HP04)] and [Pt(OH)3] (259,260). Chloride-based baths have been superseded by P-Salt-based baths, which are more stable and relatively easily prepared. Q-Salt baths offer even greater stabiUty and produce hard, bright films of low porosity. Plating under alkaline conditions employs salts of [Pt(OH3)] . These baths are easily regenerated but have low stabiUty. Platinum films have uses in the electronics industry for circuit repair, mask repair, platinum siUcide production, and interconnection fabrication (94). Vapor deposition of volatile platinum compounds such as [Pt(hfacac)2] and... 

Platinum compounds are the most active catalysts for hydrosilylation. Compounds such as and PtCl2(CH2CHCOCH2)2 are effective. In the... 

Platinum compounds Hydrosilation cross-linking of silicone polymers Hydrogenation, isomerization and hydroformylation of alkenes Automobile exhaust catalyst Sensitization dermatitis... 

Soluble salts (except certain halogeno-platinum compounds) as Pt o.oo ... 

Plastics histitute of New Zealand (PINZ), 263 PLASTOMAG , magnesium oxide, 108 Platinum and Platinum Compounds, 108 PLEXIGLAS , aciylics, 108... 

The organic bases form, like ammonia, crystalline chloroplati-nates with platinic chloride of the general formula BoH,j,PtCl,). By estimating the amount of platinum present in the salt, it is possible to calculate the molecular weight of the platinum compound, and consequently that of the base. 

There is significant metal-metal bonding in the platinum compound, whose geometry involves a square of platinum atoms another important difference is that the coordination geometry is square planar in palladium acetate but octahedral in the platinum analogue. Different oligomers exist in solution, broken down by adduct formation. Palladium(II) acetate may be obtained as brown crystals from the following reaction [65] ... 

Compared with the plethora of platinum(IV) compounds, the palladium(IV) complexes are as yet relatively few in number [10, 11]. When isolable, they tend to resemble the corresponding platinum compounds. 

Figure 3.116 Platinum compounds studied for possible anti-tumour activity. I, ris-Dichlorodi-ammineplatinum(II) cisplatin, platinol NSC 119875 neoplatin platinex. II, a.s-Diammine(l,l-cyclobutanedicarboxylato)platinum(II) JM-8 paraplatin NSC 241240. Ill, Oxiplatin. IV, Tetraplatin. V, Amminediacetatodichloro(cyclohexylamine)platinum(IV). VI, cis-Dich oro-trans-dihydroxy-cis-bis(isopropylamine)platinum(IV) iproplatin JM-19 CHIP NSC 256927.

Platinum Compounds. Several Pt compds, including trimethylplatinum derivatives are explosively unstable (Ref 9). Ammipentahydroxo-platinum, H8NOsPt, explds fairly violently above 250°, as does the pyridine analogue (Ref 3). Ammonium Hexachloroplatinate(2-),... 

Related platinum compounds such as 69 have thus been synthesized from a-keto or cyano-stabilized ylides. A selective C-coordination trans to the P phosphorus atom of the ligand is observed, probably resulting from steric interactions. 

Typical absorbers contain 50-700 mg cm of natural platinum. The observed experimental line widths in Pt (99 keV) spectra range from values close to the natural width (2F at (99 keV) = 16.28 mm s ) to 25 mm s. With respect to the line width, the 130 keV transition with a natural width of (130 keV) = 3.40 mm s seems to be more favorable for the study of hyperfine interaction in platinum compounds in practice, experimental line widths of 3.4 0.4 [328] and 3.5 0.7 mm s [329] have been measured. The considerably higher energy resulting in a much smaller recoiUess fraction and the lower probability for the population... 

Table 7.12 Isomer shift 5 (with respect to the source of Au in Pt metal at 4.2 K), line width F, and percentage resonance effect / from Pt (99 keV) Mdssbauer measurements on platinum compounds at 4.2 K by Riiegg and coworkers [329, 332, 333]...

Hypersensitivity reactions have occurred with all cancer chemotherapeutic agents. Reactions are most common with the taxanes, platinum compounds, asparaginases, and epipodophyllotoxins.7 Reactions range from mild (e.g., flushing and rashes) to severe (e.g., dyspnea, bronchospasm, urticaria, and hypotension). IgE-mediated type I reactions are the most common. To reduce the risk, patients are routinely pre-medicated... 

The starting point of this article is the discovery by Rosenberg and his collaborators of the activity of certain platinum compounds as antitumour agents (7). Here we wish to introduce the chemistry of these agents, which will be relatively familiar to inorganic chemists, but not to chemists and biochemists of other disciplines. At the same time we wish the inorganic chemist to see the relevance of the chemistry to biological fields. 

Table 2. Lytic effects of platinum compounds on E.coli Tau strain (3)...

The main uses for platinum are as a catalyst in the catalytic converter and in fuel cells. And of course platinum, a very expensive metal, is used in jewellery. However, certain platinum-containing compounds are chemotherapeutic agents, examples being cisplatin, carboplatin and oxaliplatin. This explains the synthetic interest in platinum compounds. 

Fig. 2. Relaxation modulus G(t) of a set of polydimethylsiloxane samples with increasing extent of crosslinking plotted against time of crosslinking. The linear PDMS chains (Mn 10 000, polydis-persity index 2) were endlinked with a four-functional silane crosslinker catalyzed by a platinum compound. Samples with different extent of reaction were prepared by poisoning the reaction at different times. The actual extent of reaction was not determined. Two of the samples are clearly before the gel point (LST) and two beyond. The third sample is very close to the gel point. Data of Chambon and Winter [5] evaluated by Baumgartel and Winter [8]...

Fig. 26. Tan 3 of a crosslinking PBD (Mw = 18 000) as a function of reaction time [31]. Parameter is the frequency co. The polymer is vulcanized at the pendant vinyl units with a bifunctional silane crosslinker using a platinum compound as catalyst. The curves intersect at the gel point resulting in...

See related metal oxalates See other platinum compounds... 

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