On Predicting Mössbauer Parameters of Iron-Containing Molecules with Density-Functional Theory

The performance of six frequently used density functional theory (DFT) methods (RPBE, OLYP, TPSS, B3LYP, B3LYP*, and TPSSh) in the prediction of Mössbauer isomer shifts(δ) and quadrupole splittings (ΔEQ) is studied for an extended and diverse set of Fe complexes. In addition to the influence of the applied density functional and the type of the basis set, the effect of the environment of the molecule, approximated with the conducting-like screening solvation model (COSMO) on the computed Mössbauer parameters, is also investigated. For the isomer shifts the COSMO-B3LYP method is found to provide accurate δ values for all 66 investigated complexes, with a mean absolute error (MAE) of 0.05 mm s–1 and a maximum deviation of 0.12 mm s–1. Obtaining accurate ΔEQ values presents a bigger challenge; however, with the selection of an appropriate DFT method, a reasonable agreement can be achieved between experiment and theory. Identifying the various chemical classes of compounds that need different treatment allowed us to construct a recipe for ΔEQ calculations; the application of this approach yields a MAE of 0.12 mm s–1 (7% error) and a maximum deviation of 0.55 mm s–1 (17% error). This accuracy should be sufficient for most chemical problems that concern Fe complexes. Furthermore, the reliability of the DFT approach is verified by extending the investigation to chemically relevant case studies which include geometric isomerism, phase transitions induced by variations of the electronic structure (e.g., spin crossover and inversion of the orbital ground state), and the description of electronically degenerate triplet and quintet states. Finally, the immense and often unexploited potential of utilizing the sign of the ΔEQ in characterizing distortions or in identifying the appropriate electronic state at the assignment of the spectral lines is also shown

Preparation of (-)-Levoglucosenone from Cellulose Using Sulfuric Acid in Polyethylene Glycol

(-)-Levoglucosenone (LGO, 1). Polyethylene glycol 4000 (PEG) (200 g) (Note 2) is ground to a course powder (Figure 1) in a mortar (φ: 200 mm) and pestle (203 mm) and placed in a 500 mL beaker. A diluted solution of sulfuric acid (2.50 g, 25.5 mmol) in methanol (15 mL) (Note 3) is added at ambient temperature (22 °C) and the powder is mixed using a large spatula (18 cm) to distribute the acid into the powdered PEG and allowing most of the methanol to evaporate. Cellulose powder (50 g, 308 mmol of monomer) (Note 4) is added and the powders combined by stirring with the spatula for three minutes giving an intimate mixture of PEG/acid and cellulose powders (Figure 2). The powder mixture is transferred using a large powder funnel into a 1 L three-necked, round-bottomed flask. The left neck is equipped with a distillation head with the water-cooled Liebig condenser and 100 mL receiver flask. The center neck is equipped with a 29/32 cap, and the right neck is equipped with a thermocouple inserted through a 15/25 rubber septum (Figure 3). Two traps are connected to distillation setup. The first one is 100 mL two-necked flask and the second trap is a cold-finger. Each trap is cooled to -78 °C using a dry ice/methanol bath

A domino ring-opening/epoxidation of 1,2-dioxines

Copyright © 2004 American Chemical SocietyWhen allowed to react with alkaline hydrogen peroxide, monocyclic 1,2-dioxines ring-open to their isomeric -hydroxyenone intermediates which are rapidly epoxidized to afford trans-4-hydroxy-2,3-epoxyketones in 21-81% yield. In the case of meso-1,2-dioxines, Co(II) complex catalyzed asymmetric ring-opening of the 1,2-dioxine may be employed to furnish enantioenriched epoxide

The State of Japanese Legal Studies in Europe

Das Ziel des Beitrages ist es, einen Überblick über den Stand der Studien zum japanischen Recht in Europa (im weiteren Sinn) zu geben. Der Artikel ist in acht Länderberichte aufgeteilt, die jeweils von einem Experten des japani­schen Rechts aus dem betreffenden Land verfasst wurden. Analysiert wird die aktuelle Situation in Italien, Frankreich, Israel, Skandinavien, Spanien, den Niederlanden, Belgien,dem Vereinigtem Königreich und in Deutschland. Es zeigt sich ein recht unterschiedliches Bild bezüglich des Interesses und Engagements in Lehre, Forschung und Praxis des japanischen Rechts. In einigen Ländern ist das Studium des Rechts Japans in die Japanologie integriert, in anderen ist es in der allgemeinen Rechts­ver­glei­chung verankert oder auch, etwas spezifischer, Teil der Studien zum ostasiatischen Recht

A concise route to branched erythrono-gamma-lactones. Synthesis of the leaf-closing substance potassium ()-(2R,3R)-2,3,4-Trihydroxy-2-methylbutanoate

© 2009 American Chemical SocietyA series of 1,2-dioxanes 3 were ring-opened with Co(SALEN)(2) to furnish lactol regioisomers 4 and 5 (86-99% yield). The lactols were oxidized to gamma-lactones 8 and 9 (72-96% yield) and deprotected to afford the 2-C- and 3-C-alkyl and aryl branched erythrono-gamma-lactones 1, 6, and 7 (65-94% yield), including the natural plant lactone (+/-)-2-C-d-methylerythrono-1,4-lactone 1. The latter compound was treated with aqueous potassium hydroxide to afford potassium (+/-)-(2R,3R)-2,3,4-trihydroxy-2-methylbutanoate 2, which is a leaf-closing substance of Leucaena leucocephalam.Daniel Sejer Pedersen, Tony V. Robinson, Dennis K. Taylor and Edward R. T. Tiekin