Tris platinum

Significant advances in organonickel chemistry followed the discovery of frtzws,fraws,fraws-(l,5,9-cyclododecatriene)nickel, Ni(cdt), and bis(l,5-cycloocta-diene)nickel Ni(cod)2 by Wilke et. al.1 In these and related compounds, in which only olefinic ligands are bonded to the nickel, the metal is especially reactive both in the synthesis of other compounds and in catalytic behavior. Extension of this chemistry to palladium and to platinum has hitherto been inhibited by the lack of convenient synthetic routes to zero-valent complexes of these metals in which mono- or diolefins are the only ligands. Here we described the synthesis of bis(l,5-cyclooctadiene)platinum, tris(ethylene)-platinum, and bis(ethylene)(tricyclohexylphosphine)platinum. The compound Pt(cod)2 (cod = 1,5-cyclooctadiene) was first reported by Muller and Goser,2 who prepared it by the following reaction sequence ... 

The X-ray structural studies of Howard, Spencer and Stone have established the platinum tris (olefin) complexes, Pt(olefin)3 [31], do indeed have the anticipated planar arrangement. Furthermore, all the known PtLj (olefin) [32] and PtL2 (acetylene) complexes have the planar conformations shown in (10) and (11). 

Formation of a siloxane network via hydrosilylation can also be initiated by a free-radical mechanism (300-302). A photochemical route makes use of photosensitizers such as peresters to generate radicals in the system. Unfor-timately, the reaction is quite sluggish. Several complexes of platinum such as (jj-cyclopentadienyl)trialkylplatinum(rV) compoimds have been found to be photoactive. The mixture of silicone polymer containing alkenyl functional groups with silicon hydride cross-linker materials and a catalytic amoimt of a cy-clopentadienylplatinum(IV) compound is stable in the dark. Under UV radiation, however, the platinum complex imdergoes rapid decomposition with release of platinum species that catalyze rapid hydrosilylation and network formation (303-308). Other UV-active hydrosilylation catalyst precursors include (acetylacetonate)Pt(CH3)3 (309), (acetylacetonate)2Pt (310-312), platinum tri-azene compounds (313,314), and other sytems (315,316). 

Monomer Production. The key industrial monomer is 2,4,6-trimethyl-2,4,6-tris-(3,3,3-trifluoropropyl)cyclotrisiloxane [2374-14-3] which is produced by the hydrosilylation of 3,3,3-trifluoropropene [677-21-4] with methyldichlorosilane [75-54-7] cataly2ed by various platinum and other noble metal compounds (eq. 3). 

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. 

Rhodium-on-carbon has also been found to bring about the formation of 2,2 -biquinoline from quinoline, the yield and the percentage conversion being similar to that obtained with palladium-on-carbon. On the other hand, rhodium-on-carbon failed to produce 2,2 -bipyridine from pyridine, and it has not yet been tried with other bases. Experiments with carbon-supported catalysts prepared from ruthenium, osmium, iridium, and platinum have shown that none of these metals is capable of bringing about the formation of 2,2 -biquinoline from quinoline under the conditions used with palladium and rhodium. ... 

This material can be used only in seawater or similar chloride-containing electrolytes. This is because the passivation of the silver at discontinuities in the platinum is dependent upon the formation of a film of silver chloride, the low solubility of which, in seawater, inhibits corrosion of the silver. This anode, consisting of Pt-lOPd on Ag, was tried as a substitute for rapidly consumed aluminium, for use as a trailing wire anode for the cathodic protection of ships hulls, and has been operated at current densities as high as 1 900 AmHowever, the use of trailing anodes has been found inconvenient with regard to ships manoeuvrability. 

Discussion. Iodine (or tri-iodide ion Ij" = I2 +1-) is readily generated with 100 per cent efficiency by the oxidation of iodide ion at a platinum anode, and can be used for the coulometric titration of antimony (III). The optimum pH is between 7.5 and 8.5, and a complexing agent (e.g. tartrate ion) must be present to prevent hydrolysis and precipitation of the antimony. In solutions more alkaline than pH of about 8.5, disproportionation of iodine to iodide and iodate(I) (hypoiodite) occurs. The reversible character of the iodine-iodide complex renders equivalence point detection easy by both potentiometric and amperometric techniques for macro titrations, the usual visual detection of the end point with starch is possible. 

Tin, nitratodiphenyltris(dimethy) sulfoxide)-structure, 1,77 Tin, nitratotris(triphenyltin)-structure, 1, 47 Tin,tetrakis(acetato)-stereochemistry, 1,94 Tin, tetrakis(diethyldithiocarbamato)-angular parameters, 1, 57 Tin, tetrakis(ethyldithiocarbamato)-angular parameters, 1, 57 Tin, tetranitrato-stereochemistry, 1, 94 Tin, tri-n-butylmethoxy-, 3, 208 Tin alkoxides physical properties, 2, 346 Tin bromide, 3, 194 Tin bromide hydrate, 3,195 Tin carboxylates, 3, 222 mixed valence, 3, 222 Tin chloride, 3, 194 hydroformylation platinum complexes, 6, 263 Tin chloride dihydrate, 3,195 Tin complexes, 3, 183-223 acetyl ace tone... 

Thiele and co-workers, who tried to prepare platinum chalcogenide halides, could neither isolate nor identify any pure, homogeneous compound (389). 

The catalyst remained stable for a long diile (over 50 h) under reaction conditions at the above ten erature. In order to try to tmderstand this interesting behavior, let us first focus our attention on the behavior of monometallic cobalt and platinum mordenite samples. 

Cyclic voltammetry is perhaps the most important and widely used technique within the field of analytical electrochemistry. With a theoretical standard hydrogen electrode at hand, one of the first interesting and challenging applications may be to try to use it to make theoretical cyclic voltammograms (CVs). In following, we set out to do this by attempting to calculate the CV for hydrogen adsorption on two different facets of platinum the (111) and the (100) facets. 

More recently, Atwood et al. developed a platinum complex of a water-soluble, bidentate phosphine ligand, cA-(TPPTS)2PtCl2 [TPPTS = tris(sodium m -benzenesuI onatc)phosphi nc, as an effective hydration... 

Tri-ra-butylphosphite, tri-ra-butylarsine, and tri-ra-butylstibine complexes of platinum(O) have been prepared by the reaction of the ligand with pt(COD)2] or, in the case of the phosphite, by reaction with [Pt(PPh3)4].38 All form four-coordinate complexes when 4 mole-equivalents of ligand are used, but when 2 or 3 mole-equivalents of the phosphite ligand are used, mixtures of three- and four-coordinate complexes are observed.38... 

Bulk electrochemical reduction of the platinum(IV) complex of the tridentate ligand l,l,l-tris(aminomethyl)ethane(tame), [Pt(tame)2]4+, leads to the quantitative formation of [Pt(tame)2]2+ (28), in which one of the amine donor groups in tame remains noncoordinated.141 The X-ray structure of the diprotonated complex [Pt(Htame)2]4+, as its tetrachlorozincate(II) salt, is also reported. 

A series of diastereomeric platinum(II) complexes of the type c -[PtL2Y2]2+ (L - 3-bromopyr-idine, quinoline, isoquinoline Y = PEt3, Y2 = dppp, (/ )-(I )-2,2 -bis(diphenylphosphino)-l, l -binaphthyl (R-( I )-binap)) have been prepared by the reaction of c -[PtY2(OTf)2] (OTf=tri-trifluoromethanesulfonate) with two equivalents of the N-donor ligand.207 Related complexes have also been studied, for example when L = pyridine.208 Restricted rotation about the Pt—N bonds in many of the complexes is usually detected by NMR spectroscopy, with only [Pt(dppp)(isoquinoline)2]2+ (65) exhibiting dynamic behavior at ambient temperatures. The PEt3... 

The first examples of five-coordinate platinum(II) complexes of the type [Pt(PR3)L]2+ (L = tris(2-(diphenylphosphino)ethyl)phosphine R = Et, OMe, OEt) (104) containing only P-donor atoms have been prepared by the reaction of [PtClL]+ with an appropriate monodentate tertiary phosphine or phosphite ligand.284 Triaryl phosphines and phosphites do not react with the precursor complex, even at elevated temperatures, most probably due to the considerable steric interactions that would occur upon the approach of the P-donor ligand to the platinum(II) center. 

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