Enaminone substitutents attached to cyclopentadienes: 3E/3Z stereochemistry of 1-metalla-1,3,5-hexatriene intermediates (M = Cr, W) as a functional criterion for the formation of cyclopentadienes and six-membered heterocycles, respectively

Reactions of NH-enaminones 2 with [2-(1-cycloalkenyl)ethynyl]carbene complexes 7 (M=W, Cr) gave tetrahydropentalenes, tetrahydroindenes, and hexahydroazulenes 8a-i, in which the NH-enaminone moiety is attached to the cyclopentadiene unit. The reaction involved formation of (3E)-1-metalla-1,3,5-hexatriene intermediates, which underwent pi cyclization faster than 3E/3Z isomerization. Tungsten complexes 12 and 13 were characterized as reaction intermediates. Compounds 8 are potentially bidentate ligands with respect to coordination both of the cyclopentadienyl and the enaminone moieties.     

Water as buffer material for gold nanocluster growth

Water molecules adsorbed on SiO2/Si(100) at 140 K to form amorphous solid water (ASW) layers were utilized as a buffer for assisting the growth of gold nanoclusters. It was shown that the average height and diameter of the clusters deposited on the silicon oxide substrate following the buffer annealing/desorption increase as the buffer layer becomes thicker and as more gold is deposited. The clusters' height and diameter were determined by tapping mode AFM and high-resolution SEM imaging, respectively. Typical heights were between 0.5 and 4.5 nm, and the diameters were in the range of 3-9 nm for ASW layer thickness of 7-100 ML and gold deposition in the range of 0.2-1.2 A. The density of the clusters decreased from 65 x 10(10) to 8 x 10(10) cm (-2) in the same buffer layer thickness range. Significantly different morphology of the clusters is obtained when compared to those formed by direct deposition of gold on the silicon oxide surface and to those grown on top of Xe as buffer material.     

Evidence for pygmy and giant dipole resonances in 130Sn and 132Sn

The dipole strength distribution above the one-neutron separation energy was measured in the unstable 130Sn and the double-magic 132Sn isotopes. The results were deduced from Coulomb dissociation of secondary Sn beams with energies around 500 MeV/nucleon, produced by in-flight fission of a primary 238U beam. In addition to the giant dipole resonance, a resonancelike structure ("pygmy resonance") is observed at a lower excitation energy around 10 MeV exhausting a few percent of the isovector E1 energy-weighted sum rule. The results are discussed in the context of a predicted new dipole mode of excess neutrons oscillating out of phase with the core nucleons.     

Reaktionen gespannter CC-einfachbindungen mit übergangsmetallen III. Die reaktionen des bicyclo [3.1.0] hex-2-en und bicyclo [4.1.0] hept-2-en mit dieisenenneacarbonyl,sowie die reaktion des Cyclo-C7H9Fe(CO)3+BF4− mit natrium-tetrahydroboranat

The structures and reactivities of novel 1,2,3,5-h⁴-pentenediyl-Fe(CO)₃ compounds, obtained from vinylcyclopropane systems and Fe₂(CO)₉, as well as from pentadienyl-Fe(CO)₃⁺ and H^? are discussed.     

Fluid limits for shortest job first with aging

Queueing Systems - We investigate fluid scaling of single-server queues operating under a version of shortest job first (SJF) where the priority level undergoes aging. That is, a job’s...     

Kaliumbestimmung nach der Perchloratmethode

Ohne Zusammenfassung     

My scientific first-born

Some vignettes from the career of Professor Bezalel Peleg.     

Eine Verallgemeinerung des Rolleschen Satzes auf komplexwertige Funktionen

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