Thermochemistry of adducts of some bivalent transition metal bromides with 4-chloroaniline

The compounds [MBr₂(p-clan)₂] (where M is Mn(II), Fe(II), Co(II), Ni(II), Cu(II) or Zn(II); p-clan = 4-chloroaniline) were synthesized and characterized by melting points, elemental analysis, thermal analysis and electronic and IR spectroscopy. The enthalpies of solution of the adducts, metal(II) bromides and 4-chloroaniline in methanol, 1.2 M aqueous HCl or 25% (v/v) 1.2 M aqueous HCl in methanol were measures and by using thermochemical cycles, the following thermochemical parameters for the adducts have been determined: the standard enthalpies for the Lewis acid/base reactions (Δ_rH°), the standard enthalpies of formation (Δ_fH°), the standard enthalpies of decomposition (Δ_DH°), the lattice standard enthalpies (Δ_MH°) and the standard enthalpies of the Lewis acid/base reactions in the gaseous phase (Δ_rH°(g)). The mean bond dissociation enthalpies of the metal(II)-nitrogen coordinated bonds and the enthalpies of adduct formation in the gaseous phase have been estimated.     

Stress and strain controlled rheometry on a concentrated lyotropic lamellar phase of AOT/Water/Iso-octane

We present the results of extensive strain- and stress-controlled rheometry performed on an AOT–water–iso-octane system, which forms lamellar structures with a high density of topological defects. In spite of different time-scales, both measurement methods, strain- and stress-controlled, are shown to be controlled by the level of strain experienced by the material. In both cases, after a complex transition, an apparent steady state is reached. Whereas both apparent steady states are identical for intermediate shear rate and shear stress following a power law, these are found to differ once the lower values of applied shear rate and shear stress are considered. The origin of this difference is discussed in terms of supplied energy to the sheared sample. I. Pignot-Paintrand is affiliated with The Université Joseph Fourier and member of the Institut de Chimie Moléculaire de Grenoble