Quantum-chemical study of hydride transfer in catalytic transformation of paraffins on zeolites

Ab initio quantum-chemical cluster calculations demonstrate that the activated complexes of hydride transfer reaction in catalytic transformations of paraffins on zeolites very much resembles adsorbed nonclassical carbonium ions. The calculated activation energies for reactions involving propane and isobutane are in reasonable agreement with experimental data.</p

Mobility and Migrations in the Rural Areas of Mediterranean EU Countries

AbstractThis chapter focuses on the ambivalent nature of contemporary migrations in European rural areas. The growing presence of immigrants in these areas is a direct result of the restructuring of agriculture and global agri-food chains. Evidence indicates that while agricultural work and rural settings are decreasingly attractive to local populations, they represent a favourable environment to international newcomers, due to the higher chances to access livelihood resources. The non-visibility and informality that characterise rural settings and agricultural work arrangements provide on the one side opportunities for employment, while also fostering illegal labour practices and situations of harsh exploitation

Electronic interactions in a new pi-extended tetrathiafulvalene dimer.

The first π-extended tetrathiafulvalene (exTTF) dimer in which the two exTTF units are covalently connected by 1,3-dithiole rings has been obtained in a multistep synthetic procedure involving the Ullmann cross-coupling reaction by using copper(i) thiophene-2-carboxylate (CuTC). The electronic spectrum reveals a significant electronic interaction between the exTTF units. The electrochemical study carried out by cyclic voltammetry in solution and in thin-layer conditions, and the electrochemical simulation and spectroelectrochemical (SEC) measurements confirm the electronic communication and show that the oxidation of dimer 14 occurs as two consecutive 2 e− processes D0–D0[RIGHTWARDS ARROW]D2+–D0[RIGHTWARDS ARROW]D2+–D2+. Theoretical calculations, performed at the B3P86/6-31G* level, confirm the experimental findings and predict that 142+ exists as a delocalized D.+–D.+ species in the gas phase and as a localized D2+–D0 species in solution (CH3CN or CH2Cl2). Oxidation of 142+ forms the tetracation 144+ which is constituted by two aromatic anthracene units bearing four aromatic, almost orthogonal 1,3-dithiolium cations