Unexpected formation of an azetidine-carborane derivative by dehydration of N-(1,12-dicarba-closo-dodecaboran-1-yl)formamide. The first X-ray structure of a 2,3-bis(imino)azetidine

Efforts to dehydrate (1,12-dicarba-closo-dodecaboran(12)-1-yl)formamide (a = 6.685(2) A, b = 12.877(4) A, c = 12.547(4) A, alpha = gamma = 90 degrees, beta = 90.724(11) degrees, V = 1080.8(6) A(3), Z = 4) resulted in the formation of a series of unexpected products. Addition of the Burgess reagent to the formamide, for example, led to the isolation of the corresponding methyl carbamate (a = 11.529(8) A, b = 11.529(8) A, c = 11.402(12) A, alpha = beta = gamma = 90 degrees, V = 1516(2) A(3), Z = 4), while treatment with triphosgene, a well-known dehydrating agent, resulted in the formation of a highly unusual 2,3-bis(p-carboranylimino)azetidine derivative. This particular compound, in the presence of Re(I), was hydrolyzed to give the corresponding amide, which is the first example of a 2,3-bis(imino)azetidine that has been characterized crystallographically (a = 38.496(13) A, b = 11.920(4) A, c = 27.523(10) A, beta = 127.050(5) degrees, V = 10079(6) A(3), Z = 8).     

The chemistry of piperidines—II: The electron-impact-induced fragmentation of 3-AZA-3-methylbicyclo[3,3,1]nonanes

The mass spectra of three series of stereoisomeric 3-aza-3-methyl-6-cycloalkylaminobicyclo[3,3,1]nonan-9-ols and related compounds including deaza analogues are reported and discussed. The spectra of some of the isomers differ characteristically and can be used to assign their configurations.     

Phosphaadamantanes as ligands for palladium catalyzed cross-coupling chemistry: library synthesis, characterization, and screening in the Suzuki coupling of alkyl halides and tosylates containing beta-hydrogens with boronic acids and alkylboranes

A 15-member library of phosphaadamantane ligands has been prepared via P-arylation of 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phosphaadamantane. Screening of this tertiary phosphine collection has allowed for the rapid determination of the most suitable ligand, specifically 1,3,5,7-tetramethyl-6-(2,4-dimethoxyphenyl)-2,4,8-trioxa-6-phosphaadamantane, for facilitating Suzuki-type couplings of alkyl halides or tosylates containing beta-hydrogens with either boronic acids or alkylboranes.     

Adsorptions-kinetik von Einzelschichten von Eieralbumin

Ohne Zusammenfassung     

Solvent–metal interactions in bis[1,2‐dicarba‐closo‐dodecaboran(12)‐1‐yl]mercury(II) dichloromethane solvate and bis[1,12‐dicarba‐closo‐dodecaboran(12)‐1‐yl]mercury(II) tetrahydrofuran solvate

The title compounds, bis­[1,2‐dicarba‐closo‐dodecaboran(12)‐1‐yl]­mercury(II) di­chloro­methane solvate, [Hg(C₂B₁₀H₁₁)₂]·CH₂Cl₂, (I), and bis­[1,12‐dicarba‐closo‐dodecaboran(12)‐1‐yl]­mercury(II) tetra­hydro­furan solvate, [Hg(C₂B₁₀H₁₁)₂]·C₄H₈O, (II), were prepared in excellent yields using a robust synthetic procedure involving the reaction of HgCl₂ with the appropriate monoli­thiocarborane. X‐Ray analysis of the products revealed strong interactions between the Hg atoms in both complexes and the respective lattice solvent. The distances between the Hg^II centers and the Cl atoms of the dichloromethane solvent molecule in the ortho‐carborane derivative, (I), and the O atom of the tetra­hydro­furan molecule in the para‐carborane complex, (II), are shorter than the sums of the van der Waals radii for Hg and Cl (3.53 Å), and Hg and O (3.13 Å), respectively, indicating moderately strong interactions. There are two crystallographically independent mol­ecules in the asymmetric unit of both compounds, which, in each case, are related by differing relative positions of the cages.     

Synthesis of mixed-donor amido/amino/siloxo ligands from symmetrical diamidosilylether ligands via a retro-Brook rearrangement and their chromium(II) complexes

The dilithio salts of two chelating diamidosilylether ligands undergo a retro-Brook rearrangement from oxygen to the amido-nitrogen, thereby directly yielding a new mixed-donor amido/amino/siloxo ligand. When reacted with chromium(II), siloxo-bridged dimers and a very strong eta(2)-(N,C(ipso)) arylamido interaction are featured.     

125-TW Ti:sapphire/Nd:glass laser system

We have demonstrated a Ti:sapphire/Nd:glass laser system that produces up to 51 J of energy in 395-fs pulses (125TW). Focusing at f/3 to a 2.5-times diffraction-limited spot results in a peak irradiance greater than 10(20) W/cm(2) . Our 40-cm-diameter gold diffraction gratings have a damage threshold of 0.42 J/cm(2) for 320-fs pulses.