Investigation of molecular alkali tetrafluorido aurates by matrix‐isolation spectroscopy

Molecular alkali tetrafluorido aurate ion pairs M[AuF4] (M=K, Rb, Cs) are produced by co‐deposition of IR laser‐ablated AuF3 and MF in solid neon under cryogenic conditions. This method also yields molecular AuF3 and its dimer Au2F6. The products are characterized by their Au–F stretching bands and high‐level quantum‐chemical calculations at the CCSD(T)/triple‐ζ level of theory. Structural changes in AuF4− associated with the coordination of the anion to different alkali cations are proven spectroscopically and discussed

Soluble Fluoridobromates as Well‐Behaved Strong Fluorination Reagents

We present a facile synthesis of the soluble fluoridobromates [NEt3Me][BrF4] and [NEt3Me][Br2F7] via fluorination of the corresponding bromide salts in acetonitrile, propionitrile or bromine. We structurally characterized the [BrF2]– anion, an intermediate during the synthesis, for the first time. Additionally, the dissolution of noble metals to form the corresponding halometallates as well as the application of [NEt3Me][BrF4] as a fluorination agent for disulfides to form pentafluorosulfanyls was studied

Preparation and Characterization of [Au(CF3)xF3−x(SIMes)] (x=1–3) Complexes

Trifluoromethylation of [AuF3(SIMes)] with the Ruppert–Prakash reagent TMSCF3 in the presence of CsF yields the product series [Au(CF3)xF3−x(SIMes)] (x=1–3). The degree of trifluoromethylation is solvent dependent and the ratio of the species can be controlled by varying the stoichiometry of the reaction, as evidenced from the 19F NMR spectra of the corresponding reaction mixtures. The molecular structures in the solid state of trans‐[Au(CF3)F2(SIMes)] and [Au(CF3)3(SIMes)] are presented, together with a selective route for the synthesis of the latter complex. Correlation of the calculated SIMes affinity with the carbene carbon chemical shift in the 13C NMR spectrum reveals that trans‐[Au(CF3)F2(SIMes)] and [Au(CF3)3(SIMes)] nicely follow the trend in Lewis acidities of related organo gold(III) complexes. Furthermore, a new correlation between the Au−Ccarbene bond length of the molecular structure in the solid state and the chemical shift of the carbene carbon in the 13C NMR spectrum is presented

Gold Teflates Revisited: from the Lewis Superacid [Au(OTeF5)3] to the Anion [Au(OTeF5)4]−

A new synthetic access to the Lewis acid [Au(OTeF5)3] and the preparation of the related, unprecedented anion [Au(OTeF5)4]− with inorganic or organic cations starting from commercially available and easy-to-handle gold chlorides are presented. In this first extensive study of the Lewis acidity of a transition metal teflate complex using different experimental and quantum chemical methods, [Au(OTeF5)3] was classified as a Lewis superacid. The solid state structure of the triphenylphosphane adduct [Au(OPPh3)(OTeF5)3] was determined, representing the first structural characterization of an adduct of this highly reactive [Au(OTeF5)3]. Therein, the coordination environment around the gold center slightly deviates from the typical square planar geometry. The related, unprecedented anion [Au(OTeF5)4]− shows a similar coordination motif

Reactivity of [AuF3(SIMes)] – Pathway to Unprecedented Structural Motifs

We report on a comprehensive reactivity study starting from [AuF3(SIMes)] to synthesize different motifs of monomeric gold(III) fluorides. A plethora of different ligands has been introduced in a mono-substitution yielding trans-[AuF2X(SIMes)] including alkynido, cyanido, azido, and a set of perfluoroalkoxido complexes. The latter were better accomplished via use of perfluorinated carbonyl-bearing molecules, which is unprecedented in gold chemistry. In case of the cyanide and azide, triple substitution gave rise to the corresponding [AuX3(SIMes)] complexes. Comparison of the chemical shift of the carbene carbon atom in the 13C{1H} NMR spectrum, the calculated SIMes affinity and the Au–C bond length in the solid state with related literature-known complexes yields a classification of trans-influences for a variety of ligands attached to the gold center. Therein, the mixed fluorido perfluoroalkoxido complexes have a similar SIMes affinity to AuF3 with a very low Gibbs energy of formation when using the perfluoro carbonyl route

Noncovalent Interactions in Halogenated Pyridinium Salts of the Weakly Coordinating Anion [Al(OTeF5)4]–

The synthesis and the first structural characterization of the halogenated pyridinium salts [C 5 F 5 NH] + , [C 5 F 4 ClNH] + , [(C 5 F 5 N) 2 H] + , [(C 5 Cl 5 N) 2 H] + of the weakly coordinating anion (WCA) [Al(OTeF 5 ) 4 ] − , showing noncovalent interactions in the solid state, are presented. The salts were characterized by the multinuclear NMR and IR spectroscopy as well as X-Ray diffraction. Hirshfeld surface analysis and solid state structures reveal various intermolecular anion-π and σ-hole interactions between the corresponding halogenated pyridinium cations and the anion [Al(OTeF 5 ) 4 ] −

Silver(i) Perfluoroalcoholates: Synthesis, Structure, and their Use as Transfer Reagents

Herein we report a general access to silver(i) perfluoroalcoholates, their structure in the solid state and in solution, and their use as transfer reagents. The silver(i) perfluoroalcoholates are prepared by the reaction of AgF with the corresponding perfluorinated carbonyl compounds in acetonitrile and are stable for a prolonged time at –18 °C. X-Ray analysis of single crystals of perfluoroalcoholate species showed that two Ag(i) centers are bridged by the alcoholate ligands. In acetonitrile solution, Ag[OCF3] forms different structures as indicated by IR spectroscopy. Furthermore, the silver(i) perfluoroalcoholates can be used as easy-to-handle transfer reagents for the synthesis of Cu[OCF3], Cu[OC2F5], [PPh4][Au(CF3)3(OCF3)], and fluorinated alkyl ethers

Evaluation des Programms Bau.Land.Partner.

EVALUATION DES PROGRAMMS BAU.LAND.PARTNER. Evaluation des Programms Bau.Land.Partner. / Dittrich-Wesbuer, Andrea (Rights reserved) ( -

Sweet Taste Is Complex: Signaling Cascades and Circuits Involved in Sweet Sensation

Sweetness is the preferred taste of humans and many animals, likely because sugars are a primary source of energy. In many mammals, sweet compounds are sensed in the tongue by the gustatory organ, the taste buds. Here, a group of taste bud cells expresses a canonical sweet taste receptor, whose activation induces Ca2+ rise, cell depolarization and ATP release to communicate with afferent gustatory nerves. The discovery of the sweet taste receptor, 20 years ago, was a milestone in the understanding of sweet signal transduction and is described here from a historical perspective. Our review briefly summarizes the major findings of the canonical sweet taste pathway, and then focuses on molecular details, about the related downstream signaling, that are still elusive or have been neglected. In this context, we discuss evidence supporting the existence of an alternative pathway, independent of the sweet taste receptor, to sense sugars and its proposed role in glucose homeostasis. Further, given that sweet taste receptor expression has been reported in many other organs, the physiological role of these extraoral receptors is addressed. Finally, and along these lines, we expand on the multiple direct and indirect effects of sugars on the brain. In summary, the review tries to stimulate a comprehensive understanding of how sweet compounds signal to the brain upon taste bud cells activation, and how this gustatory process is integrated with gastro-intestinal sugar sensing to create a hedonic and metabolic representation of sugars, which finally drives our behavior. Understanding of this is indeed a crucial step in developing new strategies to prevent obesity and associated diseases

Assessment of the anionic composition of the soil with the influence of eartworms activity

We established by capillary electrophoresis method that earthworms increase the chloride ion content and reduce the content of sulfate, nitrate and phosphate ions in experimental mesocosm soils. With increasing depth, the concentration of all anions decreases