Precursor platinum

An unusual chloronitro(bipy)(N,N -dinitroso-l,2-ethylenediaminato)platinum(IV) complex has been prepared by nitrosation of [PtCl2(en)(bipy)]Cl2.1166 Similar arylnitroso complexes of platinum(0) can be formed from nitrosobenzene and an appropriate precursor platinum(O) complex (equation 363).1167 This compound reacts with C02, CS2, alkenes and alkynes to give megacycles (equation 364).1168... 

Since these substitution reactions follow a two-term rate law, it is clear that solvent effects are very significant. Poorly coordinating solvents are benzene, carbon tetrachloride and sterically hindered alcohols and strongly coordinating solvents are water, lower alcohols, DMF, DMSO, acetonitrile and nitromethane. The first-order rate constants are greater in DMSO than in water. Since the majority of precursor platinum complexes used in synthetic and mechanistic studies are halo complexes, the replacement of halide ligands by solvent and the reversibility of this reaction are important features of platinum halide chemistry. 

Armes et al. [49] have reported the use of pH-responsive microgels based solely on 2-(diethylamino)ethyl methacrylate (DEA) as colloidal templates for the in situ synthesis of Pt nanoparticles (PtNPs). The swollen microgels can be used as nanoreactors efficient impregnation with PtNPs can be achieved by incorporating precursor platinum compounds, followed by metal reduction. Addition of platinic acid, H2PtCl6, to the latex particles causes the protonation of the tertiary amine... 

Some emphasis has been placed inthis Section on the nature of theel trified interface since it is apparent that adsorption at the interface between the metal and solution is a precursor to the electrochemical reactions that constitute corrosion in aqueous solution. The majority of studies of adsorption have been carried out using a mercury electrode (determination of surface tension us. potential, impedance us. potential, etc.) and this has lead to a grater understanding of the nature of the electrihed interface and of the forces that are responsible for adsorption of anions and cations from solution. Unfortunately, it is more difficult to study adsorption on clean solid metal surfaces (e.g. platinum), and the situation is even more complicated when the surface of the metal is filmed with solid oxide. Nevertheless, information obtained with the mercury electrode can be used to provide a qualitative interpretation of adsorption phenomenon in the corrosion of metals, and in order to emphasise the importance of adsorption phenomena some examples are outlined below. 

A particularly interesting case is that of the platinum metal group which, in addition to platinum (Pt), comprises ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), and palladium (Pd). These carbonyl halides are usually the most practical precursors for metal deposition because of their high volatility at low temperature. Indeed two of them, palladium and platinum, do not form carbonyls but only carbonyl halides. So does gold. 

CVD Reactions. The platinum halides are volatile with a decomposition pointtooclose to thevaporizati on pointtomakethempracticalfor C VD transport. Platinum canbe deposited by the decomposition of the acetylacetonate, although carbonaceous impurities remain in the deposit. The carbonyl halides, specifically dicarbonyl dichloride, are more satisfactory precursors. The decomposition reaction is as follows ... 

A mixed solution of platinum and ruthenium precursors was prepared by adding H2PtCl6 and RuClj at a certain ratio to de-ionized water. The solution was in negnated on y-alumina of size 300-... 

New aluminophosphate oxynitrides solid basic catalysts have been synthesised by activation under ammonia of an AIPO4 precursor. When the nitrogen content increases, XPS points out two types of nitrogen phosphorus bonding. The conversions in Knoevenagel condensation are related to the surface nitrogen content. Platinum supported on aluminophosphate oxynitride is an active catalyst for isobutane dehydrogenation. 

The rhenium interacts strongly with the oxygen atoms of the support and also with platinum platinum interacts less strongly with the support than rhenium. One is tempted to generalize that when one of the metals in a supported bimetallic cluster is noble and the other oxophihc, the oxophUic metal interacts more strongly with the support than the noble metal if the bimetalhc frame of the precursor is maintained nearly intact, then this metal-support interaction helps keep the noble metal highly dispersed. 

In the early work on the thermolysis of metal complexes for the synthesis of metal nanoparticles, the precursor carbonyl complex of transition metals, e.g., Co2(CO)8, in organic solvent functions as a metal source of nanoparticles and thermally decomposes in the presence of various polymers to afford polymer-protected metal nanoparticles under relatively mild conditions [1-3]. Particle sizes depend on the kind of polymers, ranging from 5 to >100 nm. The particle size distribution sometimes became wide. Other cobalt, iron [4], nickel [5], rhodium, iridium, rutheniuim, osmium, palladium, and platinum nanoparticles stabilized by polymers have been prepared by similar thermolysis procedures. Besides carbonyl complexes, palladium acetate, palladium acetylacetonate, and platinum acetylac-etonate were also used as a precursor complex in organic solvents like methyl-wo-butylketone [6-9]. These results proposed facile preparative method of metal nanoparticles. However, it may be considered that the size-regulated preparation of metal nanoparticles by thermolysis procedure should be conducted under the limited condition. 

These types of complexes, [Ag(Ci3H27COO)(PPh3)j and [Pt (Ci3H27COO)2(PPh3)2j, are also chosen as the precursors for the solvent-free controlled thermolysis to produce silver nanoparticles with average size 5.7 nm and platinum nanoparticles with average size 2.7 nm, respectively [13]. 

Yoshida and Otsuka found that platinum(O) complexes [PtLj] (26) (a L = PEtj b L = P Prj) and rhodium hydrido complexes such as [RhHLj] (L = P Prs 33, PEts), [RhiHidr-NJlPCyslJ (34), tram-[RhH(N2)(PPh Bu2)J, and [RhH(P Bu3)J, all of which carry electron-donating alkylphosphine ligands, can catalyze the water gas shift reaction under fairly mild conditions (100-150°C CO 20 kg/cm ) (Eq. 6.32) [23, 60]. Among these complexes, [RhH(P Pr3)3] (33) was the most active catalyst precursor. Several complexes were isolated from or detected in the reaction mixture... 

The stereoselective catalyzed addition of water or methanol to dimethyl acetylenedicarboxylate (DMAD) was reported to yield oxalacetic acid dimethylester or dimethyl methoxyfumarate. The catalyst precursor cis-[Pd(PMe2Ph)2(solvent)2] [BFJj was prepared from ds-[PdCl2(PMe2Ph)2] and AgBp4 (Eq. 6.54). The analogous platinum complex was not effective, however [99]. 

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