Quantum chemical investigation of the adsorption of methanol on a cluster model of faujasite

The adsorption of methanol in zeolites of the faujasite type with sodium and calcium counter ions is studied with quantum chemical methods. The zeolite is represented with a cluster model allowing calculations at the Møller-Plesset as well as the DFT level of theory. An adsorption energy of −62.4 kJ/mol is calculated at the MP2/TZVP//BP86/TZVP level of theory for one methanol molecule at one site II sodium cation. Insight into the adsorption process is obtained with a three-body decomposition which reveals a strong destabilisation of the adsorption strength by large, positive three-body terms, which is important for force field development.     

Ultrafast photofragmentation dynamics of molecular iodine driven with timed XUV and near-infrared light pulses

Photofragmentation dynamics of molecular iodine was studied as a response to the joint illumination with femtosecond 800 nm near-infrared and 13 nm extreme ultraviolet (XUV) pulses delivered by the free-electron laser facility FLASH. The interaction of the molecular target with two light pulses of different wavelengths but comparable pulse energy elucidates a complex intertwined electronic and nuclear dynamics. To follow distinct pathways out of a multitude of reaction channels, the recoil of created ionic fragments is analyzed. The delayed XUV pulse provides a way of following molecular photodissociation of I(2) with a characteristic time-constant of (55 ± 10) fs after the laser-induced formation of antibonding states. A preceding XUV pulse, on the other hand, preferably creates a 4d(-1) inner-shell vacancy followed by the fast Auger cascade with a revealed characteristic time constant τ(A2)=(23±11) fs for the second Auger decay transition. Some fraction of molecular cationic states undergoes subsequent Coulomb explosion, and the evolution of the launched molecular wave packet on the repulsive Coulomb potential was accessed by the laser-induced postionization. A further unexpected photofragmentation channel, which relies on the collective action of XUV and laser fields, is attributed to a laser-promoted charge transfer transition in the exploding molecule.     

Silver compounds in synthetic chemistry. Part 3. 4-Tetrafluoropyridyl silver(I), AgC5F4N - A reagent for redox transmetallations with group 12-14 elements

4-Tetrafluoropyridyl silver(I), AgC₅F₄N, has been obtained from Me₃SiC₅F₄N and AgF in nearly quantitative yield. Reactions with bis(triphenylphosphoranyliden)ammonium chloride, [PNP]Cl, gave crystalline material of the composition [PNP][Ag(C₅F₄N)₂]. Redox transmetallations of AgC₅F₄N and group 12-14 elements Zn, Cd, Hg, Ga, In, Sn yielded the corresponding 4-tetrafluoropyridyl element compounds. The molecular structures of [PNP][Ag(C₅F₄N)₂], Hg(C₅F₄N)₂, Ga(C₅F₄N)₃ · EtCN · H₂O, In(C₅F₄N)₃ · 2EtCN and Sn(C₅F₄N)₄ are discussed.     

A new molecular fluorescence depolarization effect: The coherence decay time of NO2

Measurements of the coherence decay of NO₂ by zero magnetic field level crossing (Hanle effect) reveal a novel depolarization effect of the fluorescence light not known from similar experiments on atoms and diatomic molecules.     

Stereospezifische Synthese von 6β,7β-Methylen-20-spirox-4-en-3,21-dion (Prorenon). Über Steroide. 235. Mitteilung

Stereospecific synthesis of 6β,7β-methylene-20-spirox-4-ene-3,21-dione A stereospecific synthesis of the highly active 6β,7β-methylene-20-spirolactone 4 (Prorenone) is described.