Interactions with Metals

Casassa S and Pisani C 1995 Atomic-hydrogen interaction with metallic lithium an ab /M/o embedded-cluster study Phys. Rev. B 51 7805... 

Underdeposit corrosion is not so much a single corrosion mechanism as it is a generic description of wastage beneath deposits. Attack may appear much the same beneath silt, precipitates, metal oxides, and debris. Differential oxygen concentration cell corrosion may appear much the same beneath all kinds of deposits. However, when deposits tend to directly interact with metal surfaces, attack is easier to recognize. 

Several products other than 2,2 -biaryls have been isolated following reaction of pyridines with metal catalysts. From the reaction of a-picoline with nickel-alumina, Willink and Wibaut isolated three dimethylbipyridines in addition to the 6,6 -dimethyl-2,2 -bipyridine but their structures have not been elucidated. From the reaction of quinaldine with palladium-on-carbon, Rapoport and his co-workers " obtained a by-product which they regarded as l,2-di(2-quinolyl)-ethane. From the reactions of pyridines and quinolines with degassed Raney nickel several different types of by-product have been identified. The structures and modes of formation of these compounds are of interest as they lead to a better insight into the processes occurring when pyridines interact with metal catalysts. 

Thus, inhibitors of corrosion in acid solution can interact with metals and affect the corrosion reaction in a number of ways, some of which may occur... 

Chemical analysis of niobium oxide indicated that the purity of the final product depends strongly on the purity of the initial solution. Account should be taken of about 0.02-0.03% wt. cationic impurities, introduced due to interactions with metal parts of the equipment. The main added impurities are Fe, Ni, Cr, which originate mostly from the stainless steel filter. The purity of the final product can be significantly increased by using a filter made of niobium or other appropriate material. Nevertheless, the material obtained using a stainless steel filter is sufficient for use in ceramic applications or as an initial material for carbide manufacture. 

There are three areas of activity in the field of arenediazonium salts in interaction with metals and transition elements which have some similarities to metals. First is the use of copper in the reactions of Sandmeyer (1884), Pschorr (1896), Gomberg-Bachmann (1924), and Meerwein (1939). Other transition metal catalysts (Ti and Pd) have been used for such reactions since the 1970s (see Secs. 10.8 and 10.9). Up to now only one intermediate has been directly identified, the aryldiazenido palladium complex (ArN2Pd(PPh3)3]+BF4 (Yamashita et al., 1980 see Sec. 10.9, Scheme 10-64). 

Borazine is isoelectronic and isostructural with benzene and may act as a six-electron donor in complex chemistry. In contrast to arene ligands of arene-transi-tion-metal complexes, coordinated borazines lose their planarity and are slightly puckered . Nevertheless, the B atoms show interactions with metal atoms. 

Oonoeming the interaction i namics of H2 (D ) with N1 surfaces in the first place we have elaborated some rnix tant differences with regcurd to the surface orientation and also with regard bo the mass of the incident molecule. The Lennard-Jcnes potential of Fig. 1 has frequently been used to model the dissociative adsorption process al-thou it provides a descriptlm only in one dimension. Eiqierimental (26) and theoretical (27) studies on H, interaction with metal surfaces suggest that the d th of the molecular potential well (%2 )... 

Our conclusion then for the oxygen interactions with metals is that because of the specific association of cluster ion intensities with particular types of oxygen rather than total coverage, the technique is not suitable for monitoring coverages or kinetics in an independent manner. Once it is established which type of oxygen a particular cluster ion is representative of, then that ion may, in favorable circumstances, be used for quantification. In the case of Ni, it seems that the negative ions are very sensitive to the initiation of oxide nucleation. In the case of W(IOO), the WOj, WO+ and WOj ions may fill a similar role. 

An elegant complementary test to mercury poison is the use of dienes as selective poisons for homogeneous catalysts, due to their strong coordination to metal centres yielding inert catalytic complexes. In addition, their interaction with metal surfaces is weak. If the presence of diene (dienemetal =1 1) inhibits the catalytic process and Hg test does not, homogeneity can be strongly supported. 

Many different chemical components in a microbiological medium may interact with metals. Results of many studies of metal toxicity are often not directly comparable due to the wide range of media... 

Experiments designed to probe these ideas have been carried out for NO colliding in high vibrational states on Au(lll). Before considering the results of these experiment, let us first look at how vibration might lead to unusual interactions with metal electrons. Molecules in vibrational states as high as NO(r = 15) undergo nuclear excursions that influence their... 

There are many examples of platinum(II) interacting with metals such as lead(II) or thallium(I) but few where the same metals interact with platinum(O). Catalano et al. have reported a series of metallocryptands such as the one shown in (11) that act as hosts for thallium(I)72 and lead(II).73 They have also reported an unsupported thallium(I) interaction with the platinum in [Pt(PR3)3] (R = Ph or R3 = Ph2py).74 The Pt Tl separations in the cryptands (2.791-2.795 A) are slightly shorter than those in the unsupported complexes (2.865-2.889 A).72,74... 

At pH 7 the. following groups of proteins are likely to interact with metal ions,... 

Diazirine is a cyclic isomer of diazomethane. According to the organometallic literature, scission of both C-N and N-N bonds can occur when diazirines interact with metal complexes. The formation of carbene ligands arises from selective cleavage of the C-N bond, whereas selective N-N bond scission results in the formation... 

With certain types of catalysts it is easy to postulate that more than one type of chemisorption site may exist on the solid surface. For example, in the case of metal oxide catalysts, one might speculate that certain species could chemisorb by interaction with metal atoms at the surface, while other species could interact with surface oxygpn atoms. Consider the possibility that species A adsorbed on one type of site will react with species B adsorbed on a second type of site according to the following reaction. 

Contact with fluorine leads to ignition, and interaction with metal chlorates or oxides is violent. 

In the two previous sections, evidence has been presented concerning the chemisorbed states formed when benzene interacts with metal surfaces. It is not the intention in this Section to discuss benzene hydrogenation in detail, but rather to enquire whether studies of this hydrogen-addition reaction provide information about the chemisorbed state of benzene. 

Thiol-containing molecules can interact with metal ions and metal surfaces to form dative bonds. Dative bonds also are known as coordinate covalent bonds. They differ from normal... 

P. Estrela, P. Migliorato, H. Takiguchi, H. Fukushima, and S. Nebashi, Electrical detection of biomolecular interactions with metal-insulator-semiconductor diodes. Biosens. Bioelectron. 20, 1580-1586 (2005). 

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