Electron Transfer in the Cs⊂{Mn4Fe4} Cubic Switch: A Soluble Molecular Model of the MnFe Prussian-Blue Analogues

A mixed-valence {Mn^II₃Mn^IIIFe^II₂Fe^III₂} cyanide-bridged molecular cube hosting a caesium cation, Cs⊂{Mn₄Fe₄}, was synthesized and structurally characterized by X-ray diffraction. Cyclic-voltammetry measurements show that its electronic state can be switched between five different redox states, which results in a remarkable electrochromic effect. Magnetic measurements on fresh samples point to the occurrence of a spin-state change near room temperature, which could be ascribed to a metal-to-metal electron transfer converting the {Fe^II−CN−Mn^III} pair into a {Fe^III−CN−Mn^II} pair. This feature was only previously observed in the polymeric MnFe Prussian-blue analogues (PBAs). Moreover, this novel switchable molecule proved to be soluble and stable in organic solvents, paving the way for its integration into advanced materials.     

Specific fibre composition and metabolism of the <Emphasis Type="Italic">rectus abdominis</Emphasis> muscle of bovine Charolais cattle

Background  

An important variability of contractile and metabolic properties between muscles has been highlighted. In the literature, the majority of studies on beef sensorial quality concerns M. longissimus thoracis. M. rectus abdominis (RA) is easy to sample without huge carcass depreciation and may appear as an alternative to M. longissimus thoracis for fast and routine physicochemical analysis. It was considered interesting to assess the muscle fibres of M. rectus abdominis in comparison with M. longissimus thoracis (LT) and M. triceps brachii (TB) on the basis of metabolic and contractile properties, area and myosin heavy chain isoforms (MyHC) proportions. Immuno-histochemical, histochemical, histological and enzymological techniques were used. This research concerned two populations of Charolais cattle: RA was compared to TB in a population of 19 steers while RA was compared to LT in a population of 153 heifers.     

Electronic structures of electron-rich octahedrally condensed transition-metal chalcogenide clusters

The electronic structures of some electron-rich octahedrally condensed transition-metal chalcogenide clusters are analyzed with the aid of extended Hückel and density functional molecular orbital calculations. A simple orbital approach is developed to analyze the electron counts of these clusters, which do not obey any existing electron-counting rules. Different electron counts are allowed, depending upon the nature of the metal. Optimal counts are discussed. Metal-metal bonding is generally weak in these species. Consequently, their structural arrangements are mainly governed by metal-ligand interactions.     

Retrosynthetic analysis of fullerene C(60): structure, stereochemistry, and calculated stability of C(30) fragments.

The total number of possible retrosynthetic bisections of C(60) leads to nine different isometric C(30) fragments. These molecules include five chiral units, four of which derive from partitions corresponding to four distinct "Coupes du Roi". The energies, curvatures, and homodesmotic stabilization energies of the C(30) fragments are evaluated at the ab initio 6-31G level.     

α'β-Elimination and wittig rearrangement of the carbanion from benzyl cyclooctyl ether

Beside the Wittig rearrangement and the migration of the cyclooctyl radical to the para position, the title carbanion gives rise to an elimination in a syn process.     

Théorie des processus stochastiques généraux applications aux surmartingales

Sans résuméCe nous est un très agréable devoir d'adresser ici nos plus vifs remerciements à Monsieur J. Paris qui a bien voulu, avec une bienveillance toute particulière, veiller au meilleur déroulement de ce travail, partie de notre thèse de doctorat défendue à l'Université Catholique de Louvain.Nous sommes également très reconnaissants à Monsieur P.A. Meyer, qui nous a signalé la seconde partie du théorème 12.     

The electronic structure of sulphur chloride penta-fluoride

The electronic structure of SCIF₅ is computed within the framework of the CNDO/2 approximation on the basis of Kewley's microwave geometrical data and is compared with our previous results on SF₆. The charge distribution and the value of the dipole moment are discussed as a function of the F-S-F_ax angle and an inversion of the net charge on Cl is observed when passing through the 95° value for (F-S-F_ax) angle.     

Solid-phase, multicomponent reactions of methyleneaziridines: synthesis of 1,3-disubstituted propanones

[reaction: see text] Polymer-supported methyleneaziridines undergo ring opening by Grignard reagents under copper catalysis to yield metalloenamines which are alkylated in situ to yield ketimines. Filtration and washing of these Merrifield resin-bound intermediates prior to hydrolysis provides the corresponding 1,3-disubstituted propanones in a high state of purity without recourse to column chromatography.     

Simple enantiospecific syntheses of the C(2)-diastereomers of omuralide and 3-methylomuralide

[reaction: see text] Syntheses of two novel omuralide derivatives are described.