Hydrogen magnetic susceptibility

Laachir, A., Perrischon, V., Badri, A., Lamotte, J., Catherine, E., Lavalley, J.C., El Fallah, J., Hilaire, L., Le Normand, F., Quemere, E., Sauvion, G.N., and Touret, O. 1991. Reduction of Ce02 by hydrogen. Magnetic susceptibility and Fourier-transform infrared, ultraviolet and x-ray photoelectron spectroscopy measurements. J. Chem. Soc. Faraday Trans. 87 1601-10. 

Huckel s theory initiated a wealth of experimental work, all of which fitted with the prediction of enhanced stabilization in (4n + 2)7t-systems. The measure of variegated physical and chemical quantities (such as heats of combustion and hydrogenation, magnetic susceptibilities, electronic spectra and the proclivity to react in Diels-Alder reactions) was found to correlate with the extent of aromatic character, as estimated by the theoretical methods 86). 

Metallic appearance in massive form, black to metallic color in powdered state or in electrodeposited form hexagonal crystal system density 20.53 g/cm3 hardness (Brinell) 250 melts at 3,180°C vaporizes at 5,627°C (estimated) vapor pressure 4.6x10- torr at 2,500°C electrical resistivity 19.14 microhm -cm modulus of elasticity 67x10 psi at 20°C specific magnetic susceptibility 0.369x10 thermal neutron absorption cross section 86 barns/atom superconductivity transition temperature 1.7°K insoluble in water and hydrochloric acid soluble in dilute nitric acid and hydrogen peroxide slightly soluble in sulfuric acid. 

The upheld shifts observed with cyclopropanes are probably related to their large observed magnetic susceptibilities,112 which is similar to that found for benzene. The different sense of the NMR shifts for benzene (downheld) and cyclopropane (upheld) is merely due to the different geometrical arrangement of the hydrogens in the two. The shift in benzene has been attributed... 

The nc value for palladium-hydrogen is 0.25 from magnetic susceptibility measurements (52) with Tc = 564°K (52), and from P-C-T data, de Ribaupierre and Manchester (26) estimate nc = 0.29 and Tc = 566°K. The Bragg-Williams approximation gives a reasonable WfiH value by using an average value of nc, the critical temperature, and an analytical expression for ie(n) determined... 

The hydrogen atoms thus liberated to the surface may then react with either gaseous ethylene [50,51], or associatively adsorbed ethylene [53] or with the surface C2H4. complex [52]. Volumetric [52,54] and magnetic susceptibility measurements [55] suggest that the extent of dissociation is dependent upon the temperature and varies from metal to metal. 

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