Sulla caratterizzazione delle curve di diramazione dei piani tripli

Sunto. Si caratterizzano le curve di diramazione di una classe di piani tripli più ampia di altra già trattata.     

Electrochemistry of transition metal complexes of Schiff base compartmental ligands

Summary The electrochemical behaviour of a series of mononuclear and dinuclear complexes of dioxouranium(VI), nickel(II) and copper(II) ions with the Schiff base, H₄fsalacen, derived from the condensation of 3-formylsalicylic acid and 1,2-diaminoethane, is reported.The potentially hexadentate compartmental ligand H₄fsalacen has an outer O₂O₂ and an inner N₂O₂ coordination site. The redox properties of the metal ions in these two different and adjacent chambers have been investigated and compared with those of the analogous complexes with the ligand H₄ aapen, obtained by reaction ofo-acetoacetylphenol and 1,2-diaminoethane.A preliminary report was presented at the 1st International Conference on the Chemistry and Technology of the Lanthanides and Actinides, Venice, 5 September, 1983, Italy.     

Nonadiabatic dynamics of O(1D) + N2(X1Σg+) → O(3P) + N2(X1Σg+) on three coupled potential surfaces: symmetry, Coriolis, spin-orbit, and Renner-Teller effects

We present the spin-orbit (SO) and Renner-Teller (RT) quantum dynamics of the spin-forbidden quenching O((1)D) + N(2)(X(1)Σ(g)(+)) → O((3)P) + N(2)(X(1)Σ(g)(+)) on the N(2)O X(1)A', ?(3)A", and b(3)A' coupled PESs. We use the permutation-inversion symmetry, propagate coupled-channel (CC) real wavepackets, and compute initial-state-resolved probabilities and cross sections σ(j(0)) for the ground vibrational and the first two rotational states of N(2), j(0) = 0 and 1. Labeling symmetry angular states by j and K, we report selection rules for j and for the minimum K value associated with any electronic state, showing that ?(3)A" is uncoupled in the centrifugal-sudden (CS) approximation at j(0) = 0. The dynamics is resonance-dominated, the probabilities are larger at low K, σ(j(0)) decrease with the collision energy and increase with j(0), and the CS σ(0) is lower than the CC one. The nonadiabatic interactions play different roles on the quenching dynamics, because the X(1)A'-b(3)A' SO effects are those most important while the ?(3)A"-b(3)A' RT ones are negligible.     

Copper(II) complexes of 2-chloro- and 2-bromo 1,3,4-thiadiazoles

Summary A series of copper(II) complexes of 2-X-1,3,4-thiadiazoles, of the types Cu(XL)_1.5X₂, Cu(XL)₂X₂ and Cu(XL)_4– (ClO₄)₂ · nH₂O (X = Cl or Br) has been investigated by electronic, infrared and e.p.r. spectroscopies, thermal analyses (TG and DTG) and magnetic moment measurements. The complexes have tetragonal or square pyramidal stereochemistry with CuN₄X₂ (X = Cl, Br or O) and CuN₃Cl₂ chromophores, respectively.     

High performance liquid chromatography on the chiral stationary phase (R,R)-DACH-DNB using carbon dioxide-based eluents

Fast and efficient separations of chiral stereolabile compounds were obtained at very low temperature on a π-acid chiral stationary phase (R,R-DACH-DNB) using carbon dioxide-based mobile phases containing alcoholic polar modifiers. Furthermore, efficient separations of the newly discovered spherical carbon cluster buckminsterfullerene (C₆₀) and the related higher fullerenes (C₇₀, etc.) have been performed on the same stationary phase using eluents based on either n-hexane or carbon dioxide.