Platinum© complexes

The oxidative addition of aldehydes and related species to tetrakis(triphenyl-phosphine)platinum(o) has been investigated and the product is the square planar platinium(n) diacyl species  

Cook and G. S. Jauhal, Inorg. Nuclear Chem. Letters, 1967, 3, 31. 

In this case there is an oxidative addition after (a) olefin insertion in the Pt-H bond followed by (b) cleavage to yield the Pt -alkyl complex. Dissociation of the Pt complex formed yields the hydrocarbon. Studies on reductive eliminations of this type have been made for other platinum(iv) complexes, e.g. the reaction 

Giustiniani, G. Dolcetti, R. Pietropaolo, and U. Belluco, Inorg. Chem., 1969, 8, 1048. 

The success of carboplatin calls attention to the importance of pursuing possibilities for improved patient quality of life in the treatment of cancer. As both cisplatin and carboplatin require intravenous administration, patient comfort could be further facilitated by use of an orally available platinum complex. A collaborative programme among the Johnson Matthey Technology Centre, Bristol Myers Squibb, and the Section of Drug Development at the Institute of Cancer Research (Sutton) has resulted in the discovery of a novel class of 

JM216 has now undergone phase I clinical evaluation according to both single dose and daily x 5 schedules. In agreement with the rodent data, myelosuppression has been the dose limiting toxicity, with no observations of nephro- or neurotoxicity. Worldwide phase II/III clinical trials are now ongoing. 

In nonaqueous solution such a diferrocenyl complex displays a single-step two-electron oxidation, which indicates that the two ferrocene fragments are electronically independent [176]. 

The redox potentials for the electron-transfer processes exhibited by the present platinum complexes, together with those of the alkylsulfidoferrocene-platinum derivatives, analog of the previously discussed palladium species, are reported in Table 7-33. 

There is no significant variation with respect to the corresponding palladium complexes. 

Each platinum atom maintains a square planar geometry and the whole P4Pt202 core is also planar. The cyclopentadienyl rings of the two ferrocene units are staggered and deviate by 5.0° from the mutual parallel disposition. 

The present oxo-bridged and the similar chloro-bridged platinum complexes both undergo a single-step two-electron oxidation in 1,2-dichloroethane solution at potential values that are coincident with those of the corresponding palladium complexes (X = OH, E° (2-I-/4-I-) = -1-1.13 V X = Cl, ° (2-I-/4-I-) = -1-1.18 V) [164]. 

---

Pt(CO)2Cl2] is used to deposit thin films of metallic platinum on surfaces. Concentiated organic solutions of poorly defined platinum complexes of alkyl mercaptides or sulforesinates are used to coat ceramics and glass. 

Sucralfate [54182-58-0] an aluminum salt of sucrose octasulfate, is used as an antacid and antiulcer medication (59). Bis- and tris-platinum complexes of sucrose show promise as antitumor agents (60). Sucrose monoesters are used in some pharmaceutical preparations (21). A sucrose polyester is under evaluation as a contrast agent for magnetic resonance imaging (mri) (61). Oral adrninistration of this substance opacifies the gastrointestinal tract and eliminates the need for purging prior to mri. 

Salts of neodecanoic acid have been used in the preparation of supported catalysts, such as silver neodecanoate for the preparation of ethylene oxide catalysts (119), and the nickel soap in the preparation of a hydrogenation catalyst (120). Metal neodecanoates, such as magnesium, lead, calcium, and zinc, are used to improve the adherence of plasticized poly(vinyl butyral) sheet to safety glass in car windshields (121). Platinum complexes using neodecanoic acid have been studied for antitumor activity (122). Neodecanoic acid and its esters are used in cosmetics as emoUients, emulsifiers, and solubilizers (77,123,124). Zinc or copper salts of neoacids are used as preservatives for wood (125). 

Hirayaina et al. [22] have shown that polyhydrogenmethylsiloxane can bind to aluminum, copper and steel surfaces via activation with a suitable platinum complex. The attached polymer promotes the adhesion of silicone materials whose cure involves SiH/SiVinyl hydrosilylation. Presumably, it would also be effective with other unsaturated organic polymer phases. 

Scheme 10. Addition reaction by hydrosilylation catalyzed by a platinum complex.

Because their rates of substitution tue convenient for study, most work has been done with platinum complexes, and for lhe.se it is found that ligands can be airanged in a fairly consistent order indicating their relative abilities to labilize ligands irans to themselves ... 

Several N-(chloromethyl)pyridinium platinum complexes have been described in the literature [89JOM255 92JCR(S)296 92JOM155]. Interestingly, 2-pyridyl platinum(II) complexes 11 and 12, having been dissolved in dichloromethane, are slowly N-alkylated by the solvent, yielding the N-(chloromethyl)pyridinium compounds 13 (76%) and 14 (77%) (Scheme 3). 

Organonickel derivatives also offer cases of the -coordination of the substituted hydrotrisfpyrazol- l-yl)borate ligand. For the palladium and platinum complexes, the M(II) M(IV) (M = Pd, Pt) transformation is facile. Organopalla-dium chemistry offers anew type of agostic interactions, C—H - - - Pd, where the C—H bond belongs to one of the pyrazolate rings. Cyclopalladation of various pyrazol-l-ylborates and -methanes does not modify their structure. 

Cationic BINAP-palladium and platinum complexes 30a,b can catalyze highly enantioselective cycloaddition reactions of arylglyoxals with acyclic and cyclic... 

The only prominent antitumor tetravalent platinum complex so far is iproplatin (102). In vitro it has been shown to cause interstrand DNA-breaking and cross linking. Free radical scavengers inhibit these effects. The complex is less neurotoxic and less nephrotoxic than cisplatin. Its synthesis begins with hydrogen peroxide oxidation of cis-dichlorobis(isopropvlamine) platinum (100) to the dimethylacetamide complex 101. The latter is heated in vacuum to liberate iproplatin [25]. 

---