Platinum organometallic compounds

A large number of organometallic compounds are based on transition metals Examples include organic derivatives of iron nickel chromium platinum and rhodium Many important industrial processes are catalyzed by transition metals or their complexes Before we look at these processes a few words about the structures of transition metal complexes are m order... 

The isotope patterns for two simple organometallic compounds in the molecular ion region (a) dimethylmercury and (b) dimethylplatinum. The seven isotopes of mercury show clearly and appear quite different from the six isotopes of platinum. Since there are only two carbon atoms, the contribution from C is negligible. 

Although inhibitors are deliberately added to the silicone formulation to control cure rate, unwanted cure inhibition can be caused by other species that react to form strong complexes with the platinum catalyst. Most notable of these undesired inhibitors include organotin and other organometallic compounds, sulfur, polysulfides, polysulfones or other sulfur-containing materials, amines, urethanes or amine-containing materials, unsaturated hydrocarbons in plasticizers, and some solder flux residues. 

Reactions of zerovalent platinum and palladium complexes with organometallic compounds of nontransition metals. V. I. Sokolov and O. A. Reutov, Coord. Chem. Rev., 1978, 27, 89-107 (80). 

Organometallic compounds, 14 550-551 25 71. See also Organometallics carbides contrasted, 4 648 as initiators, 14 256-257 iridium, 19 649-650 molybdenum(III), 17 27 osmium, 19 642-643 palladium, 19 652 platinum, 19 656-657 reaction with carbonyl groups, 10 505-506 rhodium, 19 645-646 ruthenium, 19 639 sodium in manufacture of, 22 777 titanium(IV), 25 105-120 Organometallic fullerene derivatives,... 

The most systematic study of reactions of transition metal atoms with halogen compounds has been the work of Klabunde on oxidation of nickel and palladium atoms. Some work has been done with copper, silver, gold, and platinum, but only scattered results have been reported for other metals. Klabunde s research has shown that perfluoroorgano-halides form isolable organometallic compounds on reaction with metal atoms much more commonly than nonfluorinated halides. The types of reactions observed with different classes of organic halides are considered next. 

The first organometallic compound of the transition metals to be characterized (1827) was Zeise s salt, K[(C2H4)PtCl3]-H20 (Fig. 18.1). It forms when K2[PtCl4] in aqueous ethanol is exposed to ethylene (ethene) a dimeric Pt—C2H4 complex with Cl bridges is also formed. In both species, the ethylene is bonded sideways to the platinum(II) center so that the two carbon atoms are equidistant from the metal. This is called the dihapto-or T]2 mode. A ligand such as an allyl radical with three adjacent carbons directly bonded to a metal atom would be trihapto- or t 3, and so on. 

Capillary electrophoresis (CE) provides high resolution for separation of chemical compounds. Separations of metal ions, of metal ions in different oxidation states and of organometallic compounds are all possible with appropriate CE conditions. This technique is being investigated for speciation. Since sample volumes in CE are generally very small, a detector capable of very low detection limits is desirable. Thus, ICP-MS has been combined with CE to provide a means for studying metal speciation. CE-ICP-MS procedures have been described for the separations of platinum species (Michalke and Schramel, 1996), selenium species (Kumar et al., 1995 Michalke and Schramel, 1996) and arsenic species (Magnuson et al., 1997). Detection limits were about 1 mgl 1 (platinum species) and 10 and 24 pg for Sclv and Scvl, respectively. An application of CE-ICP-MS to platinum species in soils is described in Section 15.8.6. 

The system is not a homogeneous one, as the organometallic compounds and alkali metal hydrides are insoluble in benzene, the solvent used however, the rate of reaction was found not to be affected by the addition of platinum or palladium catalysts. The reaction is formally similar to the base-catalyzed activations of hydrogen studied by Wilmarth this becomes clear if Eq. (45) is written as... 

Excitation to the LC states may also result in population of the CT-excited states, especially the LLCT states. These phenomena are frequently encountered in complexes containing both rc-acceptor (eg 1,10-phenantroline or 2,2 -bipyridyl) and 7r-donor ligands (eg aromatic thiols). Then the LC excitation can induce charge transfer between these ligands through central atom (LLCT) that leads to a photoredox reaction. Such reactions were reported in the case of heteroleptic organometallic compound [Rh CylLXCsHs)]3 [37], heteroleptic Re1 complex fac-[Re (L)(CO)3(bpy)]n+ [46] and metal-carbon-bonded platinum complexes [47]. 

Keywords Emission quantum yields High-resolution spectroscopy Iridium complexes OLED emitters Organometallic compounds Phosphorescence Photophysics Platinum complexes Radiative rates Spin-orbit coupling Triplet emitters Zero-field splitting SOC ZFS SOC and geometry SOC paths... 

Chemical shifts have been reported for [Me3CCH2HgX] 203) (see Table XII), tr-allylic derivatives (see Table XIII), o-cyclopentadienyl derivatives (see Table XIV), and miscellaneous compounds (see Table XV). In the case of fluxional a-cyclopentadienyl derivatives, it has been shown that chemical shifts can be used to differentiate between fluxional o-cyclopentadienyl derivatives and w-cyclopentadienyl derivatives 103). The NMR spectrum of [Sb(cyclopropyl)s] has only two carbon resonances, showing that the molecule is fluxional (56) and the NMR spectrum of the naturally occurring organometallic compound, 5 -deoxyadenosylcobalamin, has been reported (65). For a number of norbornane and allylic derivatives of palladium and platinum, a number of linear relationships have been found between chemical shifts of various carbon atoms. It was suggested that a term due to paramagnetic shielding by the metal was dominant 52b). 

There have been a number of reports of indirect coupling constants to carbon in organometallic compounds (see Tables XXXI and XXXII). Several trends are discernible. For transition metal complexes, the trends in V(i3C—M—3ip) and (i C—M— H) appear to follow those observed for V( P—M— H) and V( P—M— P). For complexes of ruthenium, osmium, rhodium, iridium, palladium, and platinum, it is generally found that V(A—M—B) (A, B = P, H) is large when... 

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