A comparison between shake-up and UV charge-transfer transitions

The He(II) spectra of the unsubstituted metallocenes {M(η-C₅H₅)₂}, M  V, Cr, Mn, Fe, Co, Ni and Ru, and of {Mn(η-C₅H₄Me)₂} are reported; both He(I) and He(II) spectra of some decamethylmetallocenes {M(η-C₅Me₅)₂}, where M  Mg, V, Cr, Mn, Fe, Co and Ni, are also given. Intensity changes between the He(I) and He(II) spectra are shown to provide a reliable guide to band assignment. A ligand field treatment of the decamethylmanganocene cation, including limited configuration interaction, gives values for Δ₂, B and C; these values are also in good agreement with the photoelectron spectra of {M(η-C₅Me₅)₂} where M  V, Cr and Fe. Overlap between the ligand and metal “d” band structures prevents complete assignment in the cases of Co and Ni.     

Homogeneous catalytic hydrogenation of free carboxylic acids in the presence of cluster ruthenium carbonyl hydrides

Saturated monocarboxylic acids up to C₆, several bicarboxylic acids and some of the corresponding anhydrides are hydrogenated in the homogeneous phase with H₄Ru₄(CO)₈(PBu₃)₄ as catalyst to give the corresponding alcohols (present among the reaction products as esters) or lactones at 100–200°C under a pressure of 100–200 atm of hydrogen. Anhydrides react at temperatures lower than those needed for acids. Esters are not reduced. Only δ-valerolactone is hydrogenated to 1,5-pentanediol. Ruthenium carbonyl carboxylates have been recovered at the end of the reaction and appear to be catalytically active intermediates.     

Electrochemical behaviour of 1-benzyl-3-carbamoylpyridinium chloride,a NAD+ model compound

In aqueous media, 1-benzyl-3-carbamoylpyridinium ion undergoes an initially reversible one-electron reduction to produce a free radical, which irreversibly dimerises to a 4,4′-linked diastereoisomeric pair. At more negative potential, the free radical undergoes a further one-electron reduction to a mixture of 1,6- and 1,4-dihydropyridine derivatives. At sufficiently positive potential the dimers can be oxidised back to pyridinium cation. The dimeric products are strongly adsorbed on the electrode surface, also at potential values where 2e products are formed, and this is a preparative drawback for the dimers and the dihydropyridines. Such problems can be overcome by the addition of benzene and of surface-active substances respectively. A detailed mechanism of the electrochemical reduction of 1-benzyl-3-carbamoylpridinium ion is proposed.     

Über das Verhalten der Normalteiler unter Projektivitäten

Ohne Zusammenfassung     

MS-Xα study of the KCl: Cu− spectrum

We have interpreted the KCl:Cu^? spectrum in the context of the MS-X_α method. The results, considering only allowed electric-dipole transitions, are in good agreement with the experimental data. Four new absorption bands, peaking at 573, 390, ～324 and ～310nm, at room temperature, are reported.