The bands present in the low ionization energy region (EI <= 12 eV) of the (He I and He II) photoelectron spectra of some aromatic (R = NO2C6H4, 4; C6H5, 5; MeOC6H4, 6; n= 1) and aliphatic (R = Me, and n= 1, 2; or 2, 3) ethylsulphonyl ketones, RC(O)(CH2)nSO2Et, have been assigned to the corresponding molecular orbitals by comparison with the assignments reported for simpler related molecules. The comparison has been assisted by the determination of the geometric structure of 6. (by X-ray diffraction) and of the model compounds HC(O)CH2SO2H and p-C6H4C(O)CH2SO2CH3(by semiempirical calculations). Oppositely charged atoms of the carbonyl and ethanesulphonyl groups are separated by distances shorter than the sum of the van der Waals radii, allowing crossed charge-transfer interactions. Low symmetry allows a deep through-space and through-bond mixing among the various group orbitals, as indicated by experimental Ei values and theoretical calculations

Acetylpyridine thiosemicarbazone, HAPTSC (1), reacts with uranyl nitrate in MeOH under formation of (H 2 APTSC) 2 -[UO 2 (NO 3 ) 2 (µ-OH)] 2 (2) or [ UO 2 (APTSC)(MeOH)(MeO)] 2 (3) depending on the experimental conditions applied. Protonation of 1 and precipitation of the [UO 2 (NO 3 ) 2 (µ-OH)] 2 2Ϫ dianion as acetylpyridinium thiosemicarbazone salt is observed when the reaction is performed without the addition of a base. The metal atoms are situated in the centres of distorted hexagonal bipyramids. The UϪU distance is 3.892(1) Å . Addition of triethylamine results in deprotonation of HAPTSC and the formation of 3 which is an unusual dimer with four methanol/ methanolato ligands of two metal sites sharing two protons. The

BrazilThe 13C NMR signals for some 2ethylthio-, 2-ethylsulphinyl-and 2ethylsulphonyl-4'-substituted acetophenones were assigned. The carbonyl carbons exhibit a progressive upfield shift on going from the ketosulphides to the ketosulphoxides and to the ketosulphones. The a-methylene carbons for the three classes of compounds are shielded by almost the same amount in relation to the corresponding calculated values. The chemical shifts of the aromatic ring carbons are in close agreement with those calculated using substituent chemical shifts. KEY WORDS 13C NMR, 2-Ethylthio-, 2ethylsulphinyl-and 2-ethyl-sulphonyl-4'substituted acetophenones

Chloridrate of pyridoxine (vitamin B 6 ) reacts with UO 2 (NO 3 ) 2 ·6H 2 O in acetonitril containing triethylamine to give the complex salt [UO 2 (PN) 2 (H 2 O)]Cl 2 . The structure of the novel compound was analyzed by single crystal X-ray diffraction affording the centrosymmetric triclinic space group P1. In [UO 2 (PN) 2 -(H 2 O)] 2ϩ two zwitterionic pyridoxine molecules complex the uranium atom in a planar manner with a water molecule achieving the coordination of a semi planar pentagon. The two uranyl oxo ligands set the axis of a distorted pentagonal bipyramide. The ability of vitamin B 6 pyridoxine to react with UO 2 2ϩ allowing the chela-

No abstract