Improving selectivity in catalytic hydrodefluorination by limiting SNV reactivity

Catalytic hydrodefluorination of perfluoroallylbenzene with Cp2TiH in THF is unselective and yields a variety of previously unknown compounds, predominantly activated in the allylic position. Several different mechanisms have been examined in detail using solvent corrected (THF) DFT(M06-2X) calculations for the archetypal perfluorinated olefin perfluoropropene and perfluoroallylbenzene: (a) single electron transfer, (b) hydrometallation/fluoride elimination, (c) σ-bond metathesis (allylic or vinylic), and (d) nucleophilic vinylic substitution (SNV, w/o Ti–F contacts in the TS). SNV is shown to be a competitive mechanism to hydrometallation and proceeds via ionic species from which F-elimination is facile and unselective leading to low selectivity in polar solvents. Subsequent experiments show that selectivity can be increased in a non-polar solvent

Crystal structure of 4,4-dimethyl-2-(trifluoromethyl)-4,5-dihydro-1H-imidazole, C6H9F3N2

C6H9F3N2, monoclinic, P21/n (no. 14), a = 10.6224(9) Å, b = 11.8639(9) Å, c = 13.3139(11) Å, β = 105.903(3)°, V = 1613.6(2) Å3, Z = 8, Rgt(F) = 0.0618, wRref(F2) = 0.1629, T = 102(2) K [1–3]

Sumanenylferrocenes and their solid state self-assembly

The first ferrocene-fused organometallic compounds derived from the buckybowl sumanene (C21H12) are presented. Both compounds, sumanenylferrocene and 1,1′-disumanenylferrocene, have been synthesized by Negishi-type cross- coupling of iodosumanene and were studied crystallographically. Sumanenylferrocenes form unique packing motifs, which are both different from those of their corannulene congeners and sumanene itself

Straightforward approach to efficient oxidative DNA cleaving agents based on Cu(II) complexes of heterosubstituted cyclens

The Cu(II) complexes of cyclen and two of its heterosubstituted analogues were shown to be efficient oxidative DNA cleavers. The reactivity strongly depends on the heteroatom inserted into the macrocycle (O > S > N)

Functional polyoxometalates from solvothermal reactions of VOSO4 with tripodal alkoxides – a study on the reactivity of different “tris” derivatives

We report a study on the structure directing effects of functional groups and counterions. The aim was to find a facile and high yielding synthetic procedure to obtain polyoxometalate (POM) building blocks for post- functionalisation. Therefore, solvothermal reactions of VOSO4 with various tris(hydroxymethyl)methane derivatives in alkaline methanolic solutions were investigated. In doing so, new POM fragments were isolated and characterised. The binding modes of the functionalised tripodal alkoxides turned out to be surprisingly different

Cycloaddition Reactions of the Diphosphenyl Complex (η5-C5Me5)(CO)2Fe-P=P-Mes* (Mes* = 2,4,6-tBu3C6H2) with Hexafluoroacetone. X-Ray Structure Analyses of (η5-C5Me5)(CO) Fe P(=PMes*)OC(CF3)2CO and (η5-C5Me5)(CO)2FePP(Mes*)OC(CF3)2

Weber L, Buchwald S, Lentz D, Preugschat D, Stammler H-G, Neumann B. Cycloaddition Reactions of the Diphosphenyl Complex (η5-C5Me5)(CO)2Fe-P=P-Mes* (Mes* = 2,4,6-tBu3C6H2) with Hexafluoroacetone. X-Ray Structure Analyses of (η5-C5Me5)(CO) Fe P(=PMes*)OC(CF3)2CO and (η5-C5Me5)(CO)2FePP(Mes*)OC(CF3)2. Organometallics. 1992;11(7):2351-2353.The diphosphenyl complex (eta-5-C5Me5)-(CO)2Fe-P=P-Mes* (Mes* = 2,4,6-tBu3C6H2) undergoes a [3 + 2] dipolar cycloaddition with hexafluoroacetone to give the metalla heterocycle (eta-5-C5Me5)(CO)-Fe-P(=PMes*)OC(CF3)2C(O) with a remarkably short Fe-P bond (2.084 (4) angstrom) and an exocyclic P=P bond. When stored in solution at -40-degrees-C, this complex partly rearranges to the metalated 1-oxa-2,3-diphosphetane (eta-5-C5Me5)(CO)2Fe-P-P(Mes*)OC(CF3)2. The molecular structures of both isomers were elucidated by single-crystal X-ray analyses

Synthesis, XRD and HS-Analysis

An efficient microwave-assisted one-step synthetic route toward Mannich bases is developed from 4-hydroxyacetophenone and different secondary amines in quantitative yields, via a regioselective substitution reaction. The reaction takes a short time and is non-catalyzed and reproducible on a gram scale. The environmentally benign methodology provides a novel alternative, to the conventional methodologies, for the synthesis of mono- and disubstituted Mannich bases of 4-hydroxyacetophenone. All compounds were well-characterized by FT-IR, 1H NMR, 13C NMR, and mass spectrometry. The structures of 1-{4-hydroxy-3-[(morpholin-4-yl)methyl]phenyl}ethan-1-one (2a) and 1-{4-hydroxy-3-[(pyrrolidin-1-yl)methyl]phenyl}ethan-1-one (3a) were determined by single crystal X-ray crystallography. Compound 2a and 3a crystallize in monoclinic, P21/n, and orthorhombic, Pbca, respectively. The most characteristic features of the molecular structure of 2a is that the morpholine fragment adopts a chair conformation with strong intramolecular hydrogen bonding. Compound 3a exhibits intermolecular hydrogen bonding, too. Furthermore, the computed Hirshfeld surface analysis confirms H-bonds and π–π stack interactions obtained by XRD packing analyses

Ethnicity, voter alignment and political party affiliation - an African case: Zambia

Conventional wisdom holds that ethnicity provides the social cleavage for voting behav-iour and party affiliation in Africa. Because this is usually inferred from aggregate data of national election results, it might prove to be an ecological fallacy. The evidence based on individual data from an opinion survey in Zambia suggests that ethnicity matters for voter alignment and even more so for party affiliation, but it is certainly not the only factor. The analysis also points to a number of qualifications which are partly methodology-related. One is that the degree of ethnic voting can differ from one ethno-political group to the other depending on various degrees of ethnic mobilisation. Another is that if smaller eth-nic groups or subgroups do not identify with one particular party, it is difficult to find a significant statistical correlation between party affiliation and ethnicity - but that does not prove that they do not affiliate along ethnic lines.Wahlverhalten und Mitgliedschaft in politischen Parteien Afrikas ist nur wenig untersucht worden. Gewöhnlich wird argumentiert, dass Ethnizität als soziale Konfliktlinie das Wahlverhalten und die Parteienmitgliedschaft strukturiert. Da dieses Argument auf hoch aggregierten Wahldaten beruht, kann hier ein ökologischer Fehlschuss vorliegen. Die vorliegende Analyse beruht deshalb auf individuellen Umfragedaten aus Sambia. Das Ergebnis ist, dass Ethnizität tatsächlich eine Rolle für das Wahlverhalten und die Parteienmitgliedschaft spielt, aber keineswegs den einzigen Erklärungsfaktor darstellt. Die Analyse offenbart zudem eine Reihe von Einschränkungen und Qualifizierungen, die teilweise methodischer Natur sind. Eine ist, dass ethnisches Wahlverhalten und Parteienmitgliedschaft von einer ethnischen Gruppe zur anderen unterschiedlich ist, dass, wenn sich kleinere ethnische Gruppen oder Untergruppen mit keiner Partei identifizieren, es schwierig wird, statistisch signifikante Korrelationen zu finden - was indessen noch nicht beweist, dass Ethnizität keine Rolle spielt

The SCIP Optimization Suite 9.0

The SCIP Optimization Suite provides a collection of software packages for mathematical optimization, centered around the constraint integer programming (CIP) framework SCIP. This report discusses the enhancements and extensions included in the SCIP Optimization Suite 9.0. The updates in SCIP 9.0 include improved symmetry handling, additions and improvements of nonlinear handlers and primal heuristics, a new cut generator and two new cut selection schemes, a new branching rule, a new LP interface, and several bug fixes. The SCIP Optimization Suite 9.0 also features new Rust and C++ interfaces for SCIP, new Python interface for SoPlex, along with enhancements to existing interfaces. The SCIP Optimization Suite 9.0 also includes new and improved features in the LP solver SoPlex, the presolving library PaPILO, the parallel framework UG, the decomposition framework GCG, and the SCIP extension SCIP-SDP. These additions and enhancements have resulted in an overall performance improvement of SCIP in terms of solving time, number of nodes in the branch-and-bound tree, as well as the reliability of the solver.Comment: The release report of the SCIP Optimization Suite version 9.

Catching Element Formation In The Act

Gamma-ray astronomy explores the most energetic photons in nature to address some of the most pressing puzzles in contemporary astrophysics. It encompasses a wide range of objects and phenomena: stars, supernovae, novae, neutron stars, stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays and relativistic-particle acceleration, and the evolution of galaxies. MeV gamma-rays provide a unique probe of nuclear processes in astronomy, directly measuring radioactive decay, nuclear de-excitation, and positron annihilation. The substantial information carried by gamma-ray photons allows us to see deeper into these objects, the bulk of the power is often emitted at gamma-ray energies, and radioactivity provides a natural physical clock that adds unique information. New science will be driven by time-domain population studies at gamma-ray energies. This science is enabled by next-generation gamma-ray instruments with one to two orders of magnitude better sensitivity, larger sky coverage, and faster cadence than all previous gamma-ray instruments. This transformative capability permits: (a) the accurate identification of the gamma-ray emitting objects and correlations with observations taken at other wavelengths and with other messengers; (b) construction of new gamma-ray maps of the Milky Way and other nearby galaxies where extended regions are distinguished from point sources; and (c) considerable serendipitous science of scarce events -- nearby neutron star mergers, for example. Advances in technology push the performance of new gamma-ray instruments to address a wide set of astrophysical questions.Comment: 14 pages including 3 figure