Divalent ions platinum

Kuroda and Tarui [498] developed a spectrophotometric method for molybdenum based on the fact that MoVI catalyses the reduction of ferric iron by divalent tin ions. The plot of initial reaction rate constant versus molybdenum concentration is rectilinear in the range 0.01-0.3 mg/1 molybdenum. Several elements interfere, namely, titanium, rhenium, palladium, platinum, gold, arsenic, selenium, and tellurium. 

There are ammoniates of PtCl2, of halides of other platinum metals and of cobalt and nickel, too, some of which have been mentioned before in, Section 50. The cobalt complexes clearly show the importance of the completed d shells for the stability of the complex. Non complex compounds of trivalent cobalt are very unstable. Solutions of divalent cobalt in ammonia, however, are readily oxidized by air, because the NH3 complex of trivalent cobalt Co(NH3)6 3+ClT has eighteen electrons used in bond formation, whereas the ion Co(NH3) + would have nineteen electrons. 

Vanadium predpitates the metal from solutions of salts of gold, silver, platinum, and iridium, and reduces solutions of mercuric chloride, cupric chloride and ferric chloride to mercurous chloride, cuprous chloride, and ferrous chloride, respectively. In these reactions the vanadium passes into solution as the tetravalent ion. No precipitation or reduction ensues, however, when vanadium is added to solutions of divalent salts of zinc, cadmium, nickel, and lead. From these reactions it has been estimated that the electrolytic potential of the change, vanadium (metal)—>-tetravalent ions, is about —0 3 to —0 4 volt, which is approximately equal to the electrolytic solution pressure of copper. This figure is a little uncertain through the difficulty of securing pure vanadium.5... 

Divalent Pd forms many planar complexes with a coordination number of 4. The tetrachlorides aie quite soluble, When a solution of palladium(II) chloride is oxidized with chlorite or chlorate ion, Pd(IV) is formed, which has a coordination number of 8, The addition of NH4Q to such a solution precipitates ammonium hexachloropalladate(IV) as a red compound. It is somewhat less stable than the platinum analog. 

Divalent and tetravalent Pt probably form as many complexes as any other metal. The platinum(II) complexes are numerous with IV. S, halogens, and C. The letranitritoplatinum complexes are soluble in basic solution. Tetranitntoplatinum(II) ion is formed when a solution of plat-inum(II) chloride is boiled, at about neutral pH, with an excess of NaNO f. The ammonium salt may explode when heated. Generally, platinum-metal nitrites should be destroyed in solution. They never should be heated in the dry form. Pladnum(II) complexes most often have a coordination number of 4. Many compounds have been prepared with olefins, cyanides, nitriles, halides, isonitnles, amines, phosphines, arsines, and nitro compounds. 

The electrochemical deposition of lead dioxide provides an example of a three-phase system which is so nearly perfect that it can be analysed by the foregoing techniques, but which has some instructive non-idealities. Divalent lead ions from a wide variety of salts can be oxidised electrochemic-ally in acid or alkaline solution to give a smooth adherent deposit on inert surfaces such as platinum. Either of the two crystalline forms a or j , or possibly a mixture of them, make up the layer, according to the ionic environment. If a mixture of sodium acetate, acetic acid, and plumbous acetate is aqueous solution is used, the a form is thought to be produced exclusively [12] and ellipsometry has been used to learn more about the growth details [13]. 

A major component of the intracellular protein thiol pool is the class of inducible, cysteine-rich metallothionein (MT) proteins, important in heavy metal detoxification in eucaryotes (52). Studies of a human head and neck carcinoma cell line revealed no difference in nonprotein sulfhydryl content between parental cells and cells 30-fold resistant to cisplatin, but the latter had twofold greater levels of total protein sulfhydryl content (127). Several human and murine tumor cell lines resistant to cisplatin showed increased expression of one metallothionein, MT Ila, and increased levels of the protein (68). In addition, mouse cells transfected with the gene encoding metallothionein Ila showed a 10-fold increase in the level of MT accompanied by a 4.4-fold level of resistance to cw-DDP (68). By contrast, treatment of rats with cisplatin followed by chromatographic resolution of kidney metallothioneins showed that platinum did not elute with the MT fractions (84). Moreover, pretreatment of rats with Cd-" to induce MT production had no effect on the metabolism of platinum in kidney or liver (84). In vitro studies of the relative affinity of Cu-metallothionein for a variety of metal ions revealed very weak binding of divalent platinum... 

---