A general synthesis of 4(5)-acylimidazoles from 4-acylaminoisoxazoles.

2-Substituted-4(5)-acyl, 1,2-disubstituted 4-acyl and 1,2-disubstituted-5-acylimidazoles can be specifically prepared from 4-aminoisoxazoles.     

Arex andp incompatible observables?

Common eigenfunctions of nontrivial projectors of x and p are constructed.     

On triazoles XLVII. Synthesis of 1,3a,5,6,ωc‐pentaazacycloalka[e]acenaphthylenes

To study the influence of planar or bulky cycloalkane rings attached to the 1,3a,5,6,ωc‐pentaazaacen‐aphthylenes to the reactivity of their 4‐alkylthio group toward amines ‐ an unexpected reaction observed recently at 1,3a,5,6,10c‐pentaazaacephenanthrylenes ( 5b , n = 4) ‐ different size 1,3a,5,6,ωc‐pentaazacyclo‐alka[e]acenaphthylenes ( 5a , n = 3; 5c , n = 5; 5d , n = 6; or 5e , n = 10) were synthesised and their spectral data compared with that of 5b (n = 4). Based on the analogy of the chemical shifts of carbon atoms at position 4 with that of 5b , similar electronic structure and thus a possibility of an analogous nucleophilic attack of amines was proposed and subsequently proved by a preparative method.     

Tunneling and sterically induced ring puckering in a substituted [8]annulene anion radical

Electron paramagnetic resonance (EPR) studies have revealed that the steric interaction between the methyl hydrogens on a tert-butoxy substituent and the cyclooctatetraene (COT) ring system sterically induces a puckering of the eight-membered ring in the anion radical of tert-butoxy-COT. The induced nonplanarity of the COT ring system causes a large attenuation of the EPR coupling constants. Since the C-D bond length is slightly shorter than is the C-H bond length, replacement of the tert-butyl group with a tert-butyl-d(9) group results in less steric interaction and measurably larger electron proton coupling constants. The oscillation between the two close to planar alternating bond length (ABL) D(2d) conformers of the COT moiety was found to be extremely rapid (k > 10(12) s(-1)) and quantum mechanical tunneling is proposed to be involved.     

XPS valence bands of Ti,Zr, Nb,Mo and Hf

The XPS valence band spectra of polycrystalline Ti, Zr, Nb, Mo and Hf have been measured with a resolution of 0.6 eV. The spectra were compared with theoretical densities of states. Good agreement is achieved if the partial densities of states are considered and a many body line shape function and life time broadening are taken into account. The sigularity index determined at various core lines as well as the experimentally determined relative valence band cross sections are reported.     

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