A crystalline σ complex of copper

Over the last decades, our understanding of σ-bond activation at transition metals has progressed considerably from both fundamental and synthetic points of view thanks to the preparation and characterization of a variety of σ complexes. Here we report the synthesis and structural analysis of the first σ complex involving a coinage metal. The copper(I) complex 2 derived from the diphosphine-disilane [Ph(2)P(C(6)H(4))Me(2)Si-SiMe(2)(C(6)H(4))PPh(2)] (1) has been isolated and crystallographically characterized. The coordination of the Si-Si σ bond to copper was thoroughly analyzed by quantum-chemical methods.     

On Linear Dynamics in Quantum Calculus

In this paper, we are concerned with establishing some new elements of q-harmonic analysis. Namely, we prove a generalized q-Paley-Wiener theorem. As a consequence, we obtain some results of linear dynamics related to the symmetric q-derivative.     

Tin Tetrachloride Adducts with Arylphosphoramidates: A Multinuclear (31P, 19F,and 119Sn) NMR Characterization in Solution

Abstract

The synthesis of octahedral complexes [SnCl₄L₂] (L = R₂NP(O)(OCH₂CF₃)(O-p-tolyl): R₂N = Me₂N (1), Et₂N (2), CH₂(CH₂CH₂)₂N (3), and O(CH₂CH₂)₂N (4), or L = R₂NP(O)(OCH₂CF₃)(O-p-PhNO₂): R₂N = Me₂N (5), Et₂N (6), and O(CH₂CH₂)₂N (7) is described. The new adducts have been characterized by multinuclear (³¹P, ¹⁹F, ¹¹⁹Sn) NMR, IR spectroscopy, and elemental analyses. The solution NMR data show the presence of a mixture of cis and trans isomers. The structure of the complexes in solution was further confirmed by ¹¹⁹Sn NMR spectra, which display a triplet for each isomer, indicating an octahedrally coordinated tin center. The effects of the nature of R and Ar substituents on the donor ability of the P=O group in the ligands R₂NP(O)(OCH₂CF₃)(OAr) were investigated on the basis of ¹¹⁹Sn NMR chemical shifts and used to classify these ligands according to their Lewis basicity.     

Synthesis and Properties of Long-Chain Aromatic Telechelic Monodispersed Diols Radical-Initiated,Addition of 2-Mercaptoethanol onto α, ω Nonconjugated Dienes

Abstract

The synthesis of aromatic telechelic mono dispersed diols produced from the radical-initiated addition reaction of a twofold excess of 2-mercaptoethanol onto original α,ω nonconjugated dienes reaction is presented. These novel α,ω nonconjugated dienes were prepared by addition reaction of m-isopropyl α,α′dimethyl benzylisocyanate with mono dispersed telechelic diols obtained by fractionation of oligo(ethylene terephthalate)s. In these cases, the long chain α,ω diols were produced selectively and quantitatively. The products are soluble in most organic solvents in contrast to classical oligo (ethylene terephthlate)s and posses a lower glass transition and melting temperatures.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Figures S1-S3.     

An effective model for Lipschitz wrinkled arches

Within the framework of the Koiter's linear elastic shell theory, we study the limit model of a Lipschitz curved arch whose mid-surface is periodically waved. The magnitude and the period of the wavings are of the same order. To achieve the asymptotic analysis, we consider a mixed formulation, for which we perform a two-scale homogenization technique. We prove the convergence of the displacements, the rotation of the normal, and the membrane strain. From the limit formulation, we derive an effective model for curved critically wrinkled arches. It introduces two membrane strain functions—instead of one in the classical case—and exhibits a corrector membrane term to the coupling between the rotation of the normal and the membrane strain.     

Bis(thiocarbamates): Synthesis and Substituent Effects on the Barrier to N‐CO Rotation

The synthesis of a new series of variously substituted bis(thiocarbamates) from the addition of dithiols to isocyanates is described. These bis(thiocarbamates) were fully characterized by NMR, IR, and HRMS analyses. In addition, the effect of different substituents on the hindered rotation about the N‐CO bond in these bis‐thiocarbamates was investigated through dynamic NMR experiments.     

Modeling of fixed-bed adsorption of Cs+ and Sr2+ onto clay–iron oxide composite using artificial neural network and constant–pattern wave approach

A low-cost, non-toxic and effective adsorbent constituted by a montmorillonite coated by iron oxides (montmorillonite–iron oxide composite) was prepared to assess its effectiveness in the removal of Cs⁺ and Sr²⁺ from aqueous solution. Dynamic adsorption experiments were carried out at room temperature under the effect of various operating parameters such as bed depth Z (5–15 cm), initial cation concentration C ₀ (2–50 mg L^?1) and volumetric flow rate Q (0.5–8 mL min^?1). Column performance has been modeled with constant-pattern wave approach combined to the Freundlich isotherm model and artificial neural network (ANN) models. The time, initial cation concentration, bed depth and volumetric flow rate were chosen as the input variables whereas, the outlet concentration C _t was considered as the output variable. The developed network was found to be useful in predicting the breakthrough curves. Experimental data for the used system were well fitted with ANN than the combined constant–pattern wave approach.     

Regiospecific Synthesis of Disubstituted Pyridin‐2‐ones and Trisubstituted Phenols with Vinamidinium Salts

A highly efficient and versatile method for the synthesis of 3‐acyl‐5‐aryl or arylsulfonylpyridin‐2‐ones and 3‐alkyl‐5‐aryl‐2‐hydroxybenzamides in one step via regiospecific cyclocondensation reaction of β‐keto‐amides with vinamidinium salts is described.     

Glycerinbromal (Tribrompropionsäurealdehyd) und Tribrompropionsäure

Ohne Zusammenfassung