Nickel and Palladium

The Preparation of 2,2 -Biqltnolines with Nickel and Palladium Catalysts Percentage Conversions" and Yields ... 

Benzylamines tend to undergo hydrogenolysis with inversion over both Raney nickel and palladium, unlike benzyl-oxygen compounds I2Ia,I67o). 

Among the three commonly used metal catalysts mentioned above which activate hydrogen, nickel and palladium form hydride phases of essentially the same type. The existence of a platinum hydride has not so far been proved. 

Identify the element with the higher first ionization energy in each of the following pairs (a) iron and nickel (b) nickel and copper (c) osmium and platinum (d) nickel and palladium ... 

Nickel and palladium react with a number of olefins other than ethylene, to afford a wide range of binary complexes. With styrene (11), Ni atoms react at 77 K to form tris(styrene)Ni(0), a red-brown solid that decomposes at -20 °C. The ability of nickel atoms to coordinate three olefins with a bulky phenyl substituent illustrates that the steric and electronic effects (54,141) responsible for the stability of a tris (planar) coordination are not sufficiently great to preclude formation of a tris complex rather than a bis (olefin) species as the highest-stoichiometry complex. In contrast to the nickel-atom reaction, chromium atoms react (11) with styrene, to form both polystyrene and an intractable material in which chromium is bonded to polystyrene. It would be interesting to ascertain whether such a polymeric material might have any catal3dic activity, in view of the current interest in polymer-sup-ported catalysts (51). 

The systematic synthesis and spectral examination of a large series of complexes, M(ol)n, ra = 1-3, M = Ni or Pd, has been performed (140 -142), with special reference to the optical spectra of the products, again affirming the usefulness of the technique for observing spectral trends as a function of substituent (see later). A number of interesting points emerged from this study, some of which have already been alluded to. The optical data for the nickel and palladium complexes respectively are reported in Tables XVI and XVII. 

In nickel and palladium dithiobenzoato complexes, four-membered chelate rings are formed (366), whereas, in the corresponding phenyl-dithio acetates [M2(S2CCH2Ph)4], the dithio ligands act as bridging groups between the two metal atoms, with the formation of binuclear units (367). The molecular structure of the latter compounds shows that each metal atom is coordinated to four sulfur atoms and to the other metal atoms in a square-pyramidal geometry. Other evidence for... 

It is very likely that the difference between the nickel and palladium-catalysts corresponds to the reductive character or to the hydrogene affinity, less important for the nickel than for the palladium. 

The infrared spectra of these oxygen compounds of nickel and palladium, and of oxygen complexes of rhodium [RhX(PPh3)2(RNC)02 X = Cl, Br, I R = CgH, p-tolyl, Bu ] are also reported (67, 102). Oxygen-18 enrichment allowed definite assignments of some of the bands in these spectra. 

Stone et al. 43, 60, 61) have studied reactions of nickel and palladium isocyanides and a number of fluorocarbons which give a remarkable variety of products. With Ni(CNBu )4 and fluoroolefins [C2F4, (CF3)2C=C(CN)2 and CF2 = CFCF = CF2] themetallocyclic complexes (XXXIV), (XXXV), and (XXXVI) are observed 60,61) the complex Ni(CNBu )2(CjF5), analo-... 

The potential of C-Si and Si-H insertion processes of platinum fragments like [(dtbpm)Pt(O)] and [(dcpm)Pt(O)] with respect to stoichiometric or catalytic applications is being evaluated in our group now. The chemistry of the nickel and palladium analogs of these intermediates and of their complexes [28, 29], in accord with theoretical expectations, has turned out to be comparably unusual and exciting. This will be reported elsewhere. 

The first examples of highly active olefin polymerization catalysts based on late transition metals were nickel and palladium complexes containing bulky diimine ligands.310 312 For example, complex (120) was found to polymerize ethylene with an activity of ll,000gmmol h bar A range of PE materials with molecular weights up to 106 and... 

The rhodium catalyst has several distinct advantages over the cobalt catalyst it is much faster and far more selective. The higher rate is in process terms translated into much lower pressures (the cobalt catalyst is operated at pressures of 700 bar). Nickel- and palladium-based catalysts have also been reported, but no applications have resulted from these. The mechanism for group 10 metals has not been studied (see Section 9.3.2.3). 

Nickel and palladium complexes also catalyze the formation of the carbon-phosphorus bonds in phosphorus(V) and phosphorus(III) compounds. Indeed, this chemistry has become a common way to prepare phosphine ligands by the catalytic formation of phosphine oxides and subsequent reduction, by the formation of phosphine boranes and subsequent decomplexation, or by the formation of phosphines directly. The catalytic formation of both aryl and vinyl carbon phosphorus bonds has been accomplished. 

Organometallic complexes of copper, nickel, and palladium have been used in indole syntheses from arenes. Most of the reactions proceed under relatively mild conditions and in some cases give rise to formation of the less common 2-substituted compounds.68 Good yields of such 2-substituted derivatives are formed in reactions of o-iodoarylamines with cuprous acetylides in dimethylformamide (Scheme 41 ).69 The efficiency of this type of... 

Nickel and palladium complexes catalyze the conversion of alkyl iodides to alkylzinc iodides 30 with added diethylzinc (Scheme 28).74 Thus, for example, 1-iodooctane was converted at room temperature to n-octylzinc iodide after treatment with 2 equiv. of diethylzinc in the presence of 1.5 mol% of a palladium bis(phosphine) complex. 

Development of new methodologies for formation of carbon-carbon bonds has been one of the major tasks in organic chemistry. Obviously, organometallic compounds, particularly zinc derivatives, have found great use in such reactions. During the past several years, there have been several significant reports of nickel- and palladium-catalyzed reactions of dialkylzincs and alkylzinc halides with alkyl halides of diverse structure. A detailed account of most of these studies can be found in a recent review by Knochel et al,246... 

PJ. Kulesza, M.A. Malik, R. Schmidt, A. Smolinska, K. Miecznikowski, S. Zamponi, A. Czerwinski, M. Berrettoni, and R. Marassi, Electrochemical preparation and characterization of electrodes modified with mixed hexacyanoferrates of nickel and palladium. J. Electroanal. Chem. 487, 57-65 (2000). 

COMPARISON OF NICKEL- AND PALLADIUM-CATALYZED REACTIONS OF BUTADIENE... 

Other metals are also active under similar conditions using the same iodide based chemistry iridium, nickel, and palladium have been described. BP has announced [4] that an improved process became operative in 1996 using... 

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