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The decarbonylation of Fe[(CO).sub.5] adsorbed in monolayer and multilayer films on Au(111)/mica substrates has been induced by 0-20 eV electrons and studied by grazing incidence IR spectroscopy. Our results show that the cross sections for the initial stages of this process in as-deposited films range from 60-300 [Å.sup.2] and show considerable variations with the incident electron energy. The high sensitivity to low-energy electrons is believed to be the result of secondary reactions of anion fragments in the film with the neighbouring Fe[(CO).sub.5] moieties, leading to increasingly massive heteronuclear [Fe.sub.n][(CO).sub.m] species and progressive CO elimination. Continued exposure to the electron beam leads to the slower degradation of these newly created species into an Fe-rich deposit containing traces of CO. These traces are removed by subsequent heating to ~300 K. Fe[(CO).sub.5] films that have been subjected to temperatures exceeding 125 K have no measurable sensitivity to the electron beam in the 0-20 eV regime; this is believed to be due to the structural transformation of the as-deposited thin film structure into 3D aggregates. This structural motif presents a very limited quantity of the adsorbed Fe[(CO).sub.5] to the incident beam, and may also form a protective layer of the robust [Fe.sub.n][(CO).sub.m] species during the initial stages of exposure to the electrons. Key words: low-energy electron, Fe[(CO).sub.5], CO elimination, dissociative electron attachment, surface polymerization. La decarbonylation du Fe[(CO).sub.5] adsorbe en monocouche et en films multicouches sur des substrats de Au(III)/ mica a ete induite par des electrons de 0 a 20 eV et la reaction a ete etudiee par spectroscopie infrarouge en incidence rasante. Les resultats obtenus montrent que les sections droites des stages initiaux de ce processus dans les films tels que deposes s'etalent de 60 a 300 [Å.sup.2] et varient beaucoup avec l'energie des electrons incidents. On croit que la grande sensibilite aux electrons de faible energie resulte de reactions secondaires des fragments ioniques dans le film avec les fractions voisines de Fe[(CO).sub.5] qui conduisent a des especes [Fe.sub.n][(CO).sub.m] heteronucleaires de plus en plus massives et a une elimination progressive de CO. Une continuation de l'exposition au faisceau d'electron conduit a une degradation plus lente de ces especes nouvellement creees en depots riches en Fe contenant des traces de CO. Il est possible d'eliminer ces traces par un chauffage subsequent a environ 300 K. Les films de Fe[(CO).sub.5] qui ont ete soumis a des temperatures superieures a 125 K n'ont aucune sensibilite mesurable vis-a-vis du faisceau d'electron dans le regime 0 a 20 eV; on croit que cette situation est due a une transformation de la structure du film mince tel que depose en des agregats 3D. Ce motif structural ne represente qu'une faible quantite du Fe[(CO).sub.5] adsorbe a faisceau incident et il peut agir comme couche protectrice pour les robustes especes [Fe.sub.n][(CO).sub.m] dans les etapes initiales d'exposition aux electrons. Mots-cles : electron de faible energie, Fe[(CO).sub.5], elimination de CO, attachement dissociatif d'electron, polymerisation en surface. [Traduit par la Redaction], Introduction The growth of thin metallic films is an essential aspect in the design of reactive surfaces and in microelectronics. Among the methods of choice to deposit these films, vapour-phase [...]

Palladium-catalyzed cyclocarbonylalions of 2-iodoanilines wiih various terminal alkynes nave been carried out by the use of commercially available molybdenum hexacarbonyl as a convenient and solid carbon monoxide source. The reactions were conducted at 160°C for 30 min under microwave irradiation and in the presence of [Et.sub.3]N in THF, affording the corresponding 2-quinolone derivatives in good regioselectivities and yields. Key words: microwave, palladium, carbonylation, 2-iodoaniline, 2-quinolone. Faisant appel a des catalyseurs de palladium et de l'hexacarbonyle de molybdene disponible commercialement comrae source eommode et solide de monoxyde de carbone, on a effectue des cyclocarbonylalions de 2-iodoanilines avec divers alcynes en position terminale. Les reactions ont ete effectuees a 160°C, pendant 30 minutes, sous irradialions de micro-ondes et en presence de [Et.sub.3]N dans le THF et elles conduisent a la formation des 2-quinoleones correspondantes avec de bons rendemenis el de bonnes regioselecliviles. Mots-cles : micro-onde, palladium, carbonylation, 2-iodoaniline, 2-quinoleone., Introduction Undoubtedly, the transition-metal-catalyzed carbonylation has become one of the most important carbonyl-formation reactions in organic synthesis. (1) Particularly, palladium-catalyzed cyclocarbonylation of unsaturated substrates provides a unique, concise, and efficient [...]

Carbonylation is currently used as a marker for irreversible protein oxidative damage. Several studies indicate that carbonylated proteins are more prone to degradation than their nonoxidized counterparts. In this study, we observed that in Escherichia coli, more than 95% of the total carbonyl content consisted of insoluble protein and most were cytosolic proteins. We thereby demonstrate that, in vivo, carbonylated proteins are detectable mainly in an aggregate state. Finally, we show that detectable carbonylated proteins are not degraded in vivo. Here we propose that some carbonylated proteins escape degradation in vivo by forming carbonylated protein aggregates and thus becoming nondegradable. In light of these findings, we provide evidence that the accumulation of nondegradable carbonylated protein presented in an aggregate state contributes to the increases in carbonyl content observed during senescence.

Synthetically useful N-Fmoc amino-alkyl isothiocyanates are described by using protected amino acids and they are prepared by thiocarbonylation of the monoprotected 1,2-diamines with C[S.sub.2]/TEA/p-TsCl. The utility of the isothiocyanates for peptidomimetics synthesis is shown by using them in the preparation of a series of dithioureidopeptide esters.

The carbonylation reaction of the dimethylniobium complex (BDI)[Me.sub.2]Nb([N.sup.t]Bu) (BDI = [beta]-diketiminate) is described. The results have shown an ability to dial in specific product mixture based on very subtle modifications to the reaction conditions, however the close proximity of diverse reaction pathways for second-row transition metals have impeded the progress in these areas.

The structural and spectroscopic changes observed during reduction of (PNP)MCl [PNP = [[([t.sup.Bu.sub.2]PC[H.sub.2]Si[Me.sub.2]).sub.2]N] with Mg are described. The changes are influenced by the d-electron count on CO binding by PNP to Fe, -Co, and -Ni.

Electronic structure methods are used for studying the transition state and products of the reaction between alkyl radicals and CO coordinated in transition-metal complexes. The results have helped in understanding the mechanism of photochemical alkane carbonylation systems by using [d.sup.8]-M[L.sub.5] metal carbonyls as cocatalysts.

The synthesis, spectroscopic properties and crystal structures of a solid enol of an anhydride are described. The upfield shifts of the [delta](OH) proton on diluting the enol solutions are attributed to the interaction of the [H.sup.+] formed with the traces of water in the solvent to give [H.sub.3][O.sup.+].

The importance of the [Cr.sub.2][(CO).sub.5][([C.sub.5][R.sub.5]).sub.2] and .Cr[(CO).sub.2](ketene)([C.sub.5][R.sub.5]) as intermediates in carbonylation of N=N=CHSi[Me.sub.3] to O=C=CHSi[Me.sub.3] by .Cr[(CO).sub.3]([C.sub.5][R.sub.5]) (R=H, [CH.sub.3]) is discussed.

The Pd-catalyzed carbonylation reactions of enynols with thiols in ionic liquids, which formed monocarbonylated 6-membered-ring lactones in high yields and good regioselectivity, are described.

A rhodium-catalyzed carbonylation reaction of spiropentanes is developed, involving two different types of carbon-carbon bond cleavage processes. The reaction has helped in the synthesis of a series of 3-methylcyclopent-2-enones, one of which is used as an intermediate in the concise synthesis of (plusmn)-beta-cuparenone.

A study to show that carbonylated proteins are associated with Hsp104p-cointaining protein aggregates and that these aggregates are retained in progenitor cell during cytokinesis by a Sir2p-dependent process is conducted. Results show that deletion of HSP104 resulted in breakdown of damage asymmetry, and overproduction of Hsp104p partially restored damage retention.

The release of ring strain upon [alpha]-cleavage is shown to be a viable strategy for engineering decarbonylation reactions in crystals. The results have shown that diphenylcyclopropenone (DPCP) has undergone an efficient quantum chain reaction in the crystalline state.