Platinum , crystal structure

Ellis, J.W., Harrison, K.N., Hoye, P.A.T., Orpen, A.G., Pringle, P.G., and Smith, M.B., Water-soluble tris(hydroxymethyl)phosphine complexes with nickel, palladium, and platinum. Crystal structure of Pd P(CH2OH)3 4].cntdot.CH3, Inorg. Chem., 31, 3026, 1992. 

Table 2. Crystal Structures and Boron Coordination of Platinum Metal Borides WITH Isolated B Atoms (Owing to Defect Boron Sublattice)...

The characterization and crystal structure of the dimer [Pt2( -dppm)3] (dppm = bis(diphenyl-phosphino)methane), first reported as a deep red complex in 1978, was described by Manojlovic-Muir et al. in 1986.11 The structure, the first of its type, is made up of two parallel and almost eclipsed trigonal-planar platinum moieties bridged by three diphosphine ligands. The Pf Pt separation is 3.0225(3) A, too long to be considered a bond.11 [Pt2(//-dppm)3] catalyzes the hydrogenation/reduction of carbon dioxide with dimethylamine to give dimethylformamide12 (Equation (1)) and the reverse reaction.13... 

Zinc dithiocarbamates have been used for many years as antioxidants/antiabrasives in motor oils and as vulcanization accelerators in rubber. The crystal structure of bis[A, A-di- -propyldithio-carbamato]zinc shows identical coordination of the two zinc atoms by five sulfur donors in a trigonal-bipyramidal environment with a zinc-zinc distance of 3.786 A.5 5 The electrochemistry of a range of dialkylthiocarbamate zinc complexes was studied at platinum and mercury electrodes. An exchange reaction was observed with mercury of the electrode.556 Different structural types have been identified by variation of the nitrogen donor in the pyridine and N,N,N, N -tetra-methylenediamine adducts of bis[7V,7V-di- .vo-propyldithiocarbamato]zinc. The pyridine shows a 1 1 complex and the TMEDA gives an unusual bridging coordination mode.557 The anionic complexes of zinc tris( V, V-dialkyldithiocarbamates) can be synthesized and have been spectroscopically characterized.558... 

Rate and equilibrium constant data, including substituent and isotope effects, for the reaction of [Pt(bpy)2]2+ with hydroxide, are all consistent with, and interpreted in terms of, reversible addition of the hydroxide to the coordinated 2,2 -bipyridyl (397). Equilibrium constants for addition of hydroxide to a series of platinum(II)-diimine cations [Pt(diimine)2]2+, the diimines being 2,2 -bipyridyl, 2,2 -bipyrazine, 3,3 -bipyridazine, and 2,2 -bipyrimidine, suggest that hydroxide adds at the 6 position of the coordinated ligand (398). Support for this covalent hydration mechanism for hydroxide attack at coordinated diimines comes from crystal structure determinations of binuclear mixed valence copper(I)/copper(II) complexes of 2-hydroxylated 1,10-phenanthroline and 2,2 -bipyridyl (399). 

Complex C (Scheme 21) seems to shows stable penta-coordination for apparently very different reasons. The compound is cationic, but the counterion is a non-coordinating tetraarylborate. Interestingly, neither the dichloromethane solvent nor the diethylether present in the reaction mixture seem to coordinate to the open site in solution. The compound was crystallized from a tetrahydrofuran/pentane mixture as the tetrahy-drofuran (THF) solvate, but in the crystal structure, the THF is remote from the open site at platinum. The open site is shielded somewhat by the methyl groups of the protonated TpMe2 ligand, but it does not appear completely inaccessible. A reasonable explanation for the... 

The study of shape and crystal structure of small metallic particles is of prime importance in modern catalysis science. The relation between reactivity and structure is still not well known. The main problem in studying small metallic particles is that conventional techniques fail in the manometer diameter range. However it is possible to overcome these difficulties by the application of non-conventional methods. It is the purpose of this paper to review some of these methods and to present some results on the characterization of gold and platinum particles. 

Table 5.45. Platinum family metals crystal structures, lattice parameters and calculated densities.

The catalytic hydrosilylation by soluble platinum compounds was discovered by Speier in the late 1950 s. The catalyst he used was H2PtCl6. Other well-known catalysts are those developed by Lukevics [7] and Karstedt [8], The crystal structure of the latter complex was solved by Lappert [9], The catalysts are depicted in Figure 18.5. 

Fig. 6-1. TVo-dimensional atomic structure on the (100) plane of platinum crystals (1x1) = cubic close-packed surface plane identical with the (100) plane (5 x 20) = hexagonal dose-packed surface plane reconstructed finm the original (100) plane. [From Kolb, 1993.]...

One of palladiums unique characteristics is its abihty to absorb 900 times its own volume of hydrogen gas. When the surface of the pure metal is exposed to hydrogen gas (H ), the gas molecules break into atomic hydrogen. These hydrogen atoms then seep into the holes in the crystal structure of the metal. The result is a metallic hydride (PdH that changes palladium from an electrical conductor to a semiconductor. The compound palladium dichloride (PdCl ) also has the ability to absorb large quantities of carbon monoxide (CO). These characteristics are useful for many commercial applications. Palladium is the most reactive of all the platinum family of elements (Ru, Rh, Pd, Os, Is, and Pt.)... 

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