Platinum compounds Pt

Louis-Nicolas Vauquelin (1763-1829) discovered the pink compound tetraamminepalladium(II) tetrachloropalladate(II), [Pd(NH3)4][PdCl4].14 This compound, which contains coordinated palladium in both the cation and the anion, is still known as Vauquelin s Salt after its discoverer. The corresponding platinum compound, [Pt(NH3)4][PtCl4], was discovered by Heinrich Gustav Magnus (1802—1870).15 It constitutes the first discovered platinum ammine and is known as Magnus ... 

A square-planar coordination is also met in the monoclinic PdP2 structure (58) of the semiconducting compounds NiP2, PdP2 and PdPAs (59). The anions are tetrahedrally surrounded by two cations plus two anions (Fig. 15). Here the anions form twisted zig-zag chains, so that these phases are also polycompounds and the cations are divalent. It is noteworthy that in the corresponding platinum compounds Pt is tetravalent like in the disulfide. Application of pressure may induce this valence state also... 

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 Chloride-based baths have been superseded by P-Salt-based baths, which are more stable and relatively easily prepared.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... 

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

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-),... 

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]...

In the early development of analogs of the platinum compounds, complexes with windows of reactivity similar to the platinum complexes were examined extensively. Whereas direct Ni and Pd analogs of Pt complexes are too kinetically reactive to be of use as drugs, Ir and Os ammine... 

With a platinum compound as the source of the catalyst, the process can be viewed as beginning by oxidative addition of SiH to a low-valence form of Pt stabilized by olefin ... 

After this brief introduction, the chapter will focus on solvolysis reactions and acid-base equilibria of various platinum compounds and on species distribution of isomeric [PtCl2(NH3)2] in aqueous solution in Section 2. Binding of platinum compounds to monomeric nucleobase derivatives will be discussed in Section 3, while Section 4 pays attention to the reactions of Pt-nucleobase complexes with different nucleophiles. And finally, the interactions of Pt with DNA and defined oligonucleotides will be discussed in Section 5. 

The availability of different metal ion binding sites in 9-substituted purine and pyrimidine nucleobases and their model compounds has been recently reviewed by Lippert [7]. The distribution of metal ions between various donor atoms depends on the basicity of the donor atom, steric factors, interligand interactions, and on the nature of the metal. Under appropriate reaction conditions most of the heteroatoms in purine and pyrimidine moieties are capable of binding Pt(II) or Pt(IV) [7]. In addition, platinum binding also to the carbon atoms (e.g. to C5 in 1,3-dimethyluracil) has been established [22]. However, the strong preference of platinum coordination to the N7 and N1 sites in purine bases and to the N3 site in pyrimidine bases cannot completely be explained by the negative molecular electrostatic potential associated with these sites [23], Other factors, such as kinetics of various binding modes and steric factors, appear to play an important role in the complexation reactions of platinum compounds. 

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