Hydrogen transfer reaction on the surface of an oxide catalyst

RuO2(110) exposes two kinds of active surface species (acidic and basic centers) that govern the interaction of the gas phase in contact with the catalyst's surface. Here we will elucidate the cooperative interplay of these two active surface sites for a simple model reaction, namely the water formation over RuO2 catalysts when supplying hydrogen and oxygen from the gas phase. The bridging O atoms harvest the hydrogen from the gas phase, while the on-top O atoms pick up those adsorbed hydrogen atoms from the bridging O atoms to form water. This mechanism of hydrogen transfer is mediated by a strong hydrogen bond. Hydrogen transfer is expected to play a vital role for the whole class of catalyzed hydrogenation and dehydrogenation reactions of hydrocarbons over RuO2.     

Die Kristallstruktur von TlFeSe2 und TlFeS2

TlFeSe₂ is monoclinic, space groupC2/m–C _2h ³ ,a=11.973 Å,b=5.490 Å,c=7.110 Å, =118.2°,Z=4.TlFeS₂ is isotypic witha=11.636 Å,b=5.304 Å,c=6.799 Å, =116.7°.The crystal structure of TlFeSe₂ has been determined from single crystal diffractometer data. Isotypy of the sulfide has been confirmed from powder diffraction data. The crystal structure containing infinite linear chains of edgesharing FeX ₄-tetrahedra, and its relationship to the thio- and selenoferrates of the alkali metals are discussed. The mineral raguinite is very probably isotypic to synthetic TlFeS₂.

     

A radical mechanism for the photochemical iron pentacarbonyl catalyzed hydrogenation of octenes

A high pressure IR and UV spectroscopic study of the catalysis of hydrogenation of 1-octene by Fe(CO)₅ under UV irradiation reveals that Fe(CO)₅ and (olefin)Fe(CO)₄ are the light absorbing species. The primary photolysis product Fe(CO)₄ reacts with H₂Fe(CO)₄ to give HFe(CO)₄ radicals, which are suggested to be the active hydrogenation promoters.     

Hyperelectronic polarization in macromolecular solids

Hyperelectronic polarization may be viewed as the electrical polarization in external fields due to the pliant interaction with the charge pairs of excitons, in which the charges are molecularly separated and range over molecularly limited domains. It is particularly pronounced in molecular solids composed of long polymeric molecules having extensive regions of electronic orbital delocalization. Hyperelectronic polarization is regarded as the principal contributor to the high polarizabilities of the following five macromolecular solids: four polyacene quinone radical polymers formed by condensation of aromatic hydrocarbon derivatives with aromatic acids and poly(Cu(II)-N,N′- dimethyl rebeanate). The first four polymers at 100 hz had dielectric constants of 1800–2400, decreasing to about 58–100 at 100,000 hz, with relaxation times of 10^?3 to 10^?4 sec. A sixth polymer, a Schiff-base condensate of 1,4-napthaquinone and p-toluene diisocyanate, however, showed little hyperelectronic polarization, displaying a dielectric constant of 10, constant over 100–100,000 hz. By simple arguments it is shown that the relaxation times and the frequency response of conduction are consonant with the proposed model of charges roaming over long molecular domains (up to 4000 A.) but restricted by molecular boundaries.     

The influence of second-nearest neighbor interactions on the thermodynamic properties of B2 phases with substitutional defects

In order to explain some discrepancies between the theoretical predictions and the experimental data for the thermodynamic properties of substitutional B 2 phases,Chang's theoretical model is extended by including the influence of second-nearest neighbor interactions. For this purpose a new parameter is introduced which is defined as the ratio of the interchange energies between second-nearest and first-nearest neighbors. Theoretical equations are derived for the compositional dependence of the activity and the partial molar enthalpy. Using literature data, the following phases are re-evaluated in terms of the disorder parameter and the newly introduced parameter : -AuZn, -AuCd, -AgMg, and -NiZn. Very good agreement is found between the theoretical curves and the experimental data for the four systems. The values of obtained range from 0.0 for -NiZn to 0.5 for -AuZn. The inclusion of second-nearest neighbor interactions has little influence on the values of . It is shown that the behavior of the activity curve in -AuZn can be explained in a physically more meaningful way by including interactions between all second-nearest neighbors rather than interactions between gold substitutional defects only, as was done byLibowitz.With 5 Figures     

Reissert compound studies. XXXIX. A novel approach to the berbine and 6-azaberbine systems and related derivatives of ellipticine

A new synthetic method for the construction of the berbine, 6-azaberbine, and indoloberbine ring skeletons is reported. Treatment of heterocyclic bases such as isoquinolines, phthalazines, and ellipticine with 2-chloromethylbenzoyl chloride and trimethylsilyl cyanide gave the corresponding Reissert compounds. Treatment of these Reissert compounds with sodium hydride resulted in intramolecular cyclization with loss of hydrogen cyanide.