Reactivity of Schiff base rhenium(V) complexes with dimethylphenylphosphine

Summary The ReOX₂L(PPh₃) complexes (X = Cl or Br and L =N-methylsalicylideneiminate,N-phenylsalicylideneiminate, halfN,N-ethylenebis(salicylideneiminate) or 8-hydroxyquinolinate) react with dimethylphenylphosphine (PMe₂Ph) to give ReOX₂L(PMe₂Ph) initially by displacement of the phosphine ligand and then the ReX₂L(PMe₂Ph)₂ complexes with reduction of rhenium(V) to rhenium(III). The complexes were characterized by elemental analysis, magnetic susceptibility measurements and i.r. and¹H n.m.r. spectra.     

Electrochemistry of rhenium(V) complexes with bidentate-bidentate and tridentate-bidentate schiff base ligands

The cathodic and anodic behaviour of rhenium(V) complexes, characterized by the ReO³⁺ core, with bidentate and tridentate Schiff base ligands, has been studied in acetonitrile solvent. Cyclic voltammetry and controlled potential coulometry were the main electroanalytical techniques employed to define the electrode processes. Electrolyses were also carried out with the aim to identify the nature of the reduced and oxidized products. In particular, it was possible to isolate and characterize new rhenium(VI) complexes, containing the group ReO⁴⁺, and the possibility of obtaining stable rhenium(IV) complexes has also been proved.     

Mixed schiff base,carbonyl(phosphine)rhenium(I) complexes

Summary The Re(CO)₂(L)P₂ complexes (L=N-methylsalicylideneiminate,N-phenylsalicylideneiminate, halfN,N-ethylenebis(salicylideneiminate) or 8-hydroxyquinolinate; P=dimethyl(phenyl)phosphine or triphenylphosphine) were synthesized from the ReCl(CO)₃P₂ complexes and characterized by elemental analysis, i.r. and¹H n.m.r. spectroscopy.     

Endor and eseem study of the radical obtained by γ irradiation of a single crystal of ammonium tartrate

The radical obtained by γ irradiation of a single crystal of ammonium tartrate has been identified by paramagnetic resonance spectroscopies. The proton hyperfine coupling tensors have been obtained, from the angular dependence of the ENDOR transition frequencies. ESEEM spectra of the radical have been also obtained. The intensities of the ESEEM lines are related to the depth of the modulation, which has a dramatic angular dependence.     

Molecular Ordering in Liquid Crystals from Incoherent Quasi-Elastic Neutron Scattering

The Elastic Incoherent Structure Factor (EISF) for neutron scattering in liquid crystals has been interpreted theoretically by evaluating the correlation functions for the molecular reorientation according to the diffusion model for highly ordered fluids. It is shown that the available experimental data are compatible with the orientational distribution function predicted by the Maier-Saupe model for uniaxial mesophases provided that the long time behaviour of the correlation functions within the time scale of the experiment be properly considered.     

Phenomenological representation of triplet-exciton kinetics

A general density-matrix formulation is derived in a way suitable for the analysis of optical and magnetic effects due to the triplet-exciton kinetics in molecular crystals, in the presence of a microwave field inducing transitions among the spin levels. The expansion of the density matrix as a power series of the microwave field intensity provides a hierarchy of systems of equations, the knowledge of higher-order corrections requiring the solutions of all lower-order terms. The solutions of the zeroth-, first- and second-order equations are relevant for the calculation of polarization and delayed fluorescence effects. ESR lineshapes and DF ODMR spectral profiles, respectively.