Molecular beam study of the system Kr + HCl

Angular distributions of HCl scattered off Kr have been measured at collision energiesE ranging from 66.3 to 208.7 meV. The curves exhibit a clearly resolved damped rainbow structure. In addition time-of-flight distributions of scattered HCl were measured indicating significant energy transfer. To a part of these data (E=99 meV) the parameters of the M5 potential energy surface of Hutson and Howard [3] were fitted using the infinite order sudden approximation (IOSA) and quasi classical trajectories (QCT). A comparison of QCT and IOSA results suggests applicability of the IOSA to the present system atE=99 meV. We find a well depth of ?31.8 meV (compared to Hutson and Howard's value of ?26.5 meV) at the collinear Kr ... HCl conformation and strong indication for the existence of a secondary potential minimum at the collinear Kr ... ClH conformation. The analysis of the angular distributions based on a one channel scattering calculation leads to an isotropic potential similar to the full potential energy surface cut along the 90°-conformation rather than to the spherical average or spherical limit of the surface.     

Determination of the solubility of organic compounds. II

Summary In general, solid particles liquify when they are exposed to air laden with the vapor of a liquid in which they are soluble. There are exceptions, however, which may be explained by assuming the formation of a solvate.

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Zusammenfassung Feste Teilchen verflüssigen sich im allgemeinen, wenn sie Luft ausgesetzt sind, die mit dem Dampf einer Flüssigkeit geladen ist, in der sie löslich sind. Es wurden aber Ausnahmen gefunden, die möglicherweise durch die Bildung von Solvaten erklärt werden können.

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Résumé Généralement, les particules solides se liquéfient si elles sont exposées à l'air chargé de la vapeur d'un liquide dans lequel elles sont solubles. Il existe cependant des exceptions que l'on peut expliquer en supposant la formation de solvates.

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On the occasion of the hundredth return ofFriedrich Emich's birthday.

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The authors wish to express their appreciation to ProfessorO. F. Steinbach for his suggestions and advice.     

A Theoretical Study of Complex Formation between Formaldehyde and Lithium

Ab initio SCF and CI calculations on the cationic and neutral complexes of formaldehyde and lithium are reported. For the cationic complex CH₂O/Li⁺, the stabilization energy of 41.7 kcal/mol obtained from the SCF calculation increases to 51.6 kcal/mol if a configuration interaction is introduced. For the neutral complex CH₂O^?/Li⁺, the C_2v-conformer of the ²A₁-state with the equilibrium bond distances of d(C? O) = 1.23 Å and d (O? Li) = 1.90 Å is calculated to be more stable than the ₂B₁-state with d (C? O) = 1.34 Å, and d (O? Li) = 1.65 Å. Charge transfer and polarization effects upon complex formation are discussed.     

Combinatorial Chemistry for Ligand Development in Catalysis: Synthesis and Catalysis Screening of Peptidosulfonamide Tweezers on the Solid Phase

On the basis of a pyrrolidine tweezer 1, a library of peptidosulfonamide tweezers (15a-e, 16a-e) was synthesized on the solid phase. This library was screened in a simultaneous substrate screening procedure for the ability to enantioselectively catalyze the Ti(O-i-Pr)(4)-mediated addition of diethylzinc to aldehydes. One of the best solid-phase tweezer catalyst (i.e., 16d, giving an ee of 32% in solid-phase catalysis) was resynthesized in solution (compounds 20 and 21). The now homogeneous solution-phase catalysis showed even better enantioselectivity (i.e., up to 66%).