Ein lamellarer Schichtverband auf der Grundlage von Wasserstoffbrücken und π‐Stapelung: Kristallstruktur des Lithiumkomplexes [Li{C6H4(SO2)2N}(H2O)3] und ein Vergleich mit anderen Metall(I)‐benzol‐1, 2‐di(sulfonyl)amiden

The title complex, obtained by treating ortho‐benzenedisulfonimide (HZ) with LiOH in aqueous solution, has been characterized by low‐temperature X‐ray diffraction (triclinic, space group P&1macr;, Z' = 1). The lithium cation is bonded to one sulfonyl oxygen atom and three water molecules in a distorted tetrahedral configuration [Li‐O 189.3(3)‐201.2(3) pm, O‐Li‐O 98.5(2)‐123.2(2)?]. The zero‐dimensional [Li(Z)(H₂O)₃] complexes, which display an intramolecular O(W)‐H···O hydrogen bond, are cross‐linked via five O(W)‐H···O/N/O(W) interactions and a remarkably short C‐H···O bond (H···O 217 pm, C‐H···O 170?) to form a two‐dimensional assembly comprising an internal polar lamella of metal cations, (SO₂)₂N groups and water molecules, and hydrophobic peripheral regions consisting of protruding benzo groups. In the packing, alternate carbocycles drawn from adjacent layers set up a π‐stacking array of parallel aromatic rings (intercentroid distances 349 and 369 pm, cycle spacings 331 and 336 pm). In a short survey, the currently known crystal packings of seven M^IZ · n H₂O (n ≥ 0) complexes are examined and compared.     

Polysulfonylamine. CLIV [1] Kristallstrukturen von Metall‐di(methansulfonyl)amiden. 7 [2] Ein dreidimensionales Koordinationspolymer aus Schichten und Pfeilern: Kristallstruktur von Ba[(CH3SO2)2N]2·2H2O

Polysulfonylamines. CLIV. Crystal Structures of Metal Di(methanesulfonyl)amides. 7. A Three‐Dimensional Coordination Polymer Built up from Layers and Pillars: Crystal Structure of Ba[(CH₃SO₂)₂N]₂·2H₂O The barium compound BaA₂·2H₂O, derived from HA = di(methanesulfonyl)amine, has been characterized by single crystal X‐ray diffraction at —95 °C (monoclinic, space group P2₁/n, Z = 4). Despite numerous metal‐ligand bonds, the independent anions A^— and A′^— retain the pseudo‐C₂ symmetric conformation that commonly occurs in organic onium salts BH⁺A^—. The large cation attains ninefold coordination via interactions with one (O, N)‐chelating A^—, three κ¹O‐bonding A^—, two κ¹O‐bonding A′^— and two monodentate water molecules; if a distinctly longer barium‐water distance is included, the coordination number may alternatively be viewed as 9 + 1 and one water molecule regarded as an asymmetrically μ₂‐bridging ligand. In contrast to the previously reported layer structures of SrA₂ and PbA₂, the present crystal displays a three‐dimensional coordination assembly consisting of layers formed by the cations, the water molecules and the pentadentate A^— ligands, and of interlayer pillars provided by the bidentate A′^— ligands; however, the Ba²⁺/A^— substructure turns out to be topologically and crystallographically congruent with the corresponding M²⁺/A^— substructures in SrA₂ and PbA₂. The crystal cohesion of the barium complex is reinforced by four O(W)—H···O=S hydrogen bonds and several non‐classical C—H···O=S hydrogen bonds.     

Die ersten Röntgenstrukturen kationischer Diorganylzinn(IV)‐Dichelate [R2Sn(L–L)2]2⊕ mit zweizähnigen Phosphanoxid‐Liganden: Di(methansulfonyl)amid als nichtkoordinierendes Gegenion

Polysulfonylamines. CXI. The First X‐Ray Structures of Cationic Diorganyltin(IV) Dichelates [R₂Sn(L–L)₂]^2⊕ Involving Bidentate Phosphine Oxide Ligands: Di(methanesulfonyl)amide as a Non‐Coordinating Counter‐Ion The reaction of Me₂Sn(A)₂, where A^⊖ = (MeSO₂)₂N^⊖, with DPPOE = ethane‐1,2‐diylbis(diphenylphosphine oxide) or CDPPOET = cis‐ethene‐1,2‐diylbis(diphenylphosphine oxide) yields the ionic dichelates [Me₂Sn(dppoe)₂]^2⊕ · 2 A^⊖ ( 1 ; monoclinic, space group P2₁/c) and [Me₂Sn(cdppoet)₂]^2⊕ · 2 A^⊖ ( 2 ; monoclinic, P2₁/n). A solvated variety of 2 , [Me₂Sn(cdppoet)₂]^2⊕ · 2 A^⊖ · Et₂O · 0.15 MeCN ( 4 ; triclinic, P 1), was serendipitously obtained by thermal degradation of the new compound [Me₂Sn(A)(μ‐OH)]₂ · 2 CDPPOET in an MeCN/Et₂O medium. The crystals of 1 , 2 and 4 consist of discrete formula units (one independent unit for 1 and 2 , two independent units for 4 ); in the structure of 4 , the solvent molecules are located in lattice cavities. All the tin atoms lie on crystallographic inversion centres and display moderately distorted octahedral C₂O₄ coordinations with short Sn–O bonds in the range 218–223 pm. Within the formula units, the anions are connected to the P–CH donor groups of the chelating ligands by C–H…O/N interactions, some of which are remarkably short (e.g. in 1 : H…O 220 pm, C–H…O 170°; H…N 242 pm, C–H…N 153°).     

Staudinger – Reaktionen am Bornanylen(dimethylphosphino)methylimin. Phosphorylierung des dabei gebildeten Trimethylsilylphosphinimids mit Diorganochlorphosphinen: unerwartete Bildung von Verbindungen mit P=N–P–P-Einheiten

Staudinger Reactions with Bornanylene(dimethylphosphino)methylimine. Phosphorylation of the Trimethylsilylphosphine Imide formed with Diorganochlorophosphines: unexpected Formation of Compounds with P=N–P–P Units Phosphinimido derivatives of the chiral bornanylene(dimethylphosphino)methyl imine have been obtained from its reactions with trimethylsilyl-, phenyl- and 4-nitrobenzoyl azide. A single crystal X-ray structure determination has been conducted on the 4-nitro-benzoylphosphinimido derivative of bornanylene(dimethylphosphino)methyl imine. The compound was found to crystallize with two independent molecules in the chiral monoclinic space group P2₁. The trimethylsilylphosphinimido derivative of bornanylene(dimethylphosphino)methyl imine was allowed to react with diorgano-chlorophosphines, with unexpected formation of compounds with PP-bonded RR′₂P=N–P⁽⁺⁾R″₂–PR″₂ groups. The ³¹P-NMR spectra of two representative compounds are simulated and discussed.     

The Supramolecular Self-Assembly of Aminoglycoside Antibiotics and their Applications

Aminoglycosides, a class of antibiotics that includes gentamicin, kanamycin, neomycin, streptomycin, tobramycin and apramycin, are derived from various streptomyces species. Despite the significant increase in the antibacterial resistant pathogens, aminoglycosides remain an important class of antimicrobial drugs due to their unique chemical structure which offers a broad spectrum of activity. The modification of antibiotics and their subsequent use in supramolecular chemistry is rarely reported. Given the importance of aminoglycosides, here we give a brief overview on the modification of 4,5- and 4,6-disubstituted deoxystreptamine classes of aminoglycosides through supramolecular chemistry and their potential for real world applications. We also make the case that the work in this area is gaining momentum, and there are significant opportunities to meet the challenges of modern antibiotics through the modification of aminoglycosides by harnessing the advantages of supramolecular chemistry.     

Recent advances and comparisons between harmonic balance and Volterra-based nonlinear frequency response analysis methods

Harmonic balance and Volterra-based analysis methods are well known, but the capabilities of these methods have been limited by significant issues of complexity which either constrain their application to relatively simple cases, or limit the accuracy of analysis in more complex cases. This study briefly summarizes recent results which effectively extend the capabilities of both harmonic balance and Volterra-based analysis by making complex analyses much more feasible. The new capabilities and performance of the two approaches are then evaluated and compared using benchmark case studies of a Duffing oscillator and a nonlinear automotive damper. The results offer new insights and lead to different conclusions on the relative merits of harmonic balance versus Volterra-based analysis relative to prior studies and similar benchmark analyses.     

Applications of He neutron spin filters at the NCNR

At the NIST Center for Neutron Research (NCNR), we have applied ³He neutron spin filters (NSFs) to the instruments where ³He NSFs are advantageous, such as thermal triple-axis spectrometry, small-angle neutron scattering, and diffuse reflectometry. We present the status of our development and application of this method, including polarized gas production by spin-exchange optical pumping, magnetostatic cavities for storage of the polarized gas on the beam line, and nuclear magnetic resonance (NMR)-based, on-line monitoring and reversal of the ³He polarization. We present the status of developing user-friendly interfaces incorporated into the instrument software to handle these ³He neutron spin filters while taking data and performing data analysis. Finally we discuss the status of development of a polarization capability on the multi-axis crystal spectrometer, which requires polarization analysis over a 220° angular range.     

The SN3–SN2 spectrum. Rate constants and product selectivities for solvolyses of benzenesulfonyl chlorides in aqueous alcohols

Rate constants for a wide range of binary aqueous mixtures and product selectivities (S) in ethanol–water (EW) and methanol–water (MW) mixtures, are reported at 25 °C for solvolyses of benzenesulfonyl chloride and the 4‐chloro‐derivative. S is defined as follows using molar concentrations: S = ([ester product]/[acid product]) × ([water solvent]/[alcohol solvent]). Additional selectivity data are reported for solvolyses of 4‐Z‐substituted sulfonyl chlorides (Z = OMe, Me, H, Cl and NO₂) in 2,2,2‐trifluoroethanol–water. To explain these results and previously published data on kinetic solvent isotope effects (KSIEs) and on other solvolyses of 4‐nitro and 4‐methoxybenzenesulfonyl chloride, a mechanistic spectrum involving a change from third order to second order is proposed. The molecularity of these reactions is discussed, along with new term ‘S_N3–S_N2 spectrum’ and its connection with the better established term ‘S_N2–S_N1 spectrum’. Copyright © 2009 John Wiley & Sons, Ltd.