Experimental systems copper

Theoretical studies by Pyykkb in 1998 for [M2(NHCHNH)2] systems, M=Cu, Ag, and Au, predicted the M-M distances at the MP2 level [8]. Experimentally, systems containing amidinate ligands were known with Cu and Ag but unknown with Au. The results for the models containing silver and copper are close to the X-ray structures of [M2(ArNC(H)NAr)2], Ar=C6H4-4-Me and M=Ag, Cu. The Ag-Ag distance is 2.705 and 2.712 A and the Cu-Cu distance is 2.497 and 2.528 A at the experimental and theoretical level. Table 1.1. The hypothetical dinuclear gold(I) amidinate compound was calculated to have an Au-Au distance at the MP2 level of 2.728 A [8]. The dinuclear gold(I) amidinate complex now known proves the predicted Au-Au distance to be rather good. 

Figure 5.7 Three-dimensional drawing of the experimental system used to assess the catalytic properties of the amorphous iron silicate smokes. The (smoke) catalyst is contained in the bottom of a quartz finger (attached to a 2L Pyrex bulb) that can be heated to a controlled temperature. A Pyrex tube brings reactive gas to the bottom of the finger. The gas then passes through the catalyst into the upper reservoir of the bulb and flows through a copper tube at room temperature to a glass-walled observation cell (with ZnSe windows) in an P iiR spectrometer. From there, a closed-cycle metal bellows pump returns the sample via a second 2L bulb and the Pyrex tube to the bottom of the catalyst finger to start the cycle over again (Hill and Nuth 2003).

Par] Park, Y.-G., Gaskell, D.R., The Thermodynamic Activities of Copper and Iron in the System Copper-Iron-Platinum at 1300°C , Metall. Trans. B, 20B(4), 127-135 (1989) (Phase Diagram, Experimental, Thermodyn., 30)... 

Having derived general theoretical formulae for the probability distribution function dPy,n (equations (3.30), (3.33) and (3.34)) in the following we present the results of a statistical analysis of the distances between clusters formed on a flat electrode surface. Several authors have performed such experimental studies in different experimental systems silver [3.36-3.38], lead [3.39-3.41], mercury [3.42] and gold [3.43] on glassy carbon, copper on evaporated silver [3.44] and mercury on platinum [3.31, 3.45]. Here we comment upon the data reported in Ref. [3.38]. 

To account for the course of this reaction theoretical calculations of the coordination of ketomalonate 37 to copper(II) and zinc(II) have revealed that the six-membered ring system is slightly more stable than the five-membered ring system (Scheme 4.30). The coordination of 37 to catalyst (l )-39 shows that the six-membered intermediate is C2-symmetric with no obvious face-shielding of the carbonyl functionality (top), while for the five-membered intermediate (bottom) the carbonyl is shielded by the phenyl substituent. Calculations of the transition-state energy for the reaction of the two intermediates with 1,3-cyclohexadiene leads to the lowest energy for the five-membered intermediate this approach is in agreement with the experimental results [45]. 

The experimental investigation was performed by depositing copper films on the (100) -surface of a platinum single crystal. It was found that the reconstruction of the Pt surface was lifted upon Cu adsorption. The system was then heated to different temperatures and the formation of different ordered surface alloys was evidenced by... 

However, the experimental evidence collected during recent years, concerning mostly the nickel-copper alloy systems, complicated this almost currently accepted interpretation of the alloy catalytic behavior (45). Chemisorptive and subsequent catalytic phenomena appeared to require a different approach for elucidation. The surface reactivity had to be treated as a localized quality of the atoms at the interface, influenced by their neighbors in the crystal lattice (78-80). A detailed general discussion of catalysis on alloys is beyond the scope of this review. In the monograph by Anderson (81) and in the review by Moss and Whalley (82), recently published, a broad survey of the catalytic reactivity of alloys may be found. 

A thermal plasma system has been developed for the decomposition of methane. A schematic diagram of the experimental apparatus is shown in Fig. 1. The system consists primarily of D.C. plasma torch, plasma reactor and filter assembly. Plasma was discharged between a tungsten cathode and a copper anode using N2 gas. All the experiments were carried out at atmospheric pressure at 6 kW input electric power and N2 flow rate of 10 to 12 1/min. The feed gas (CH4) flow rates were varied from 3 to 15 1/min depending on the operating conditions, shown in Table. 1. 

In case of copper some rheological experiments carried out at a given polymer concentration and increasing amoimt of cations indicates that copper/pectin systems in the one-phase domain behave as a viscoelastic liquid rather than a viscoelastic solid referred to as true gel (G (co) = G, when to—>0 with Gg the equilibrium shear modulus)[35]. Despite the lack of experimental data the range in cation and polymer concentration in which true gels may be observed seemed very limited. These results corroborate the strength of the binding of copper by pectins evidenced by the properties of the phase separation curves. 

The stoichiometric insertion of terminal alkenes into the Cu-B bond of the (NHC)Cu-B(cat) complex, and the isolation and full characterisation of the p-boryl-alkyl-copper (I) complex has been reported. The alkyl complex decomposes at higher temperatures by P-H elimination to vinylboronate ester [67]. These data provide experimental evidence for a mechanism involving insertion of alkenes into Cu-boryl bonds, and establish a versatile and inexpensive catalytic system of wide scope for the diboration of alkenes and alkynes based on copper. 

It is particularly helpful that we can take the Cu-Ni system as an example of the use of successive deposition for preparing alloy films where a miscibility gap exists, and one component can diffuse readily, because this alloy system is also historically important in discussing catalysis by metals. The rate of migration of the copper atoms is much higher than that of the nickel atoms (there is a pronounced Kirkendall effect) and, with polycrystalline specimens, surface diffusion of copper over the nickel crystallites requires a lower activation energy than diffusion into the bulk of the crystallites. Hence, the following model was proposed for the location of the phases in Cu-Ni films (S3), prepared by annealing successively deposited layers at 200°C in vacuum, which was consistent with the experimental data on the work function. 

Most biochemically relevant high-spin systems have such short 7j-relaxation times that their EPR is broadened beyond detection at ambient temperatures. An exception is the class of S = 5/2 Mn" systems with D hx. Also, S = 7/2 Gd"1-based MRI shift reagents exhibit readily detectable room-temperature EPR spectra. Otherwise, aqueous-solution transition ion bioEPR is limited to complexes of S = 1/2 metals, in particular Cu", and to a lesser extent VIV02+, NiIn, Ni1, Mov, and Wv. Cupric is the stable oxidation state of biological copper under aerobic conditions, however, the other metals are stable as Vv, Ni", MoVI, and WVI, and, therefore, the other oxidation states associated with S = 1/2 paramagnetism may exhibit oxidative or reductive reactivity and may thus require specific experimental precautions such as strict anaerobicity over the course of the EPR experiment. 

This paper reviews the recent experimental results and mathematical modeling from the literature on electrocodeposition of particles in a metallic matrix. Although many different particle/metal systems are discussed, the electrocodeposition of alumina particles in copper matrix is highlighted as this widely-studied system illustrates the various effects of process variables and it exemplifies the types of contradictions concerning these results in the literature. 

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