Lithiierte Phosphanimin‐Komplexe. Die Kristallstrukturen von [LiCH(Me)PEt2NSiMe3]4 und des Cuprats [Li{Me3SiNPMe2CH2–Cu–CH(SiMe2OLi)PMe2NSiMe3}]2

Lithiated Phosphoraneimine Complexes. Crystal Structures of [LiCH(Me)PEt₂NSiMe₃]₄ and of Cuprate [Li{Me₃SiNPMe₂CH₂–Cu–CH(SiMe₂OLi)PMe₂NSiMe₃}]₂ [LiCH(Me)PEt₂NSiMe₃]₄ ( 1 ) has been obtained as colorless, oxygen and moisture sensitive crystals from the reaction of the silylated phosphoraneimine Me₃SiNPEt₃ with ⁿbutyllithium in ⁿhexane at 0 °C. 1 crystallizes in the tetragonal space group I4₁/acd with eight formula units per unit cell. Lattice dimensions at –80 °C: a = b = 1505.2(1), c = 4747.4(6) pm, R₁ = 0.0278. 1 forms a Li₄ tetrahedron, the faces of which are capped with the carbon atoms of the carbanionic ‐CH(Me)‐ groups. The nitrogen atoms occupy the corners of the Li₄ tetrahedron by means of “inner solvation”. The cuprate [Li{Me₃SiNPMe₂CH₂–Cu–CH(SiMe₂OLi)PMe₂NSiMe₃}]₂ ( 4 ) has been obtained from the known [LiCH₂PMe₂NSiMe₃]₄ and copper(I) iodide in the presence of silicon grease (‐OSiMe₂‐)_n in diethylether, forming colorless oxygen and moisture sensitive crystals. 4 crystallizes in the triclinic space group P 1 with one formula unit per unit cell. Lattice dimensions at –50 °C: a = 1025.4(2), b = 1145.5(2), c = 1261.0(2) pm, α = 65.19(1)°, β = 79.55(1)°, γ = 77.94(1)°, R₁ = 0.039. 4 forms a centrosymmetric dimeric molecule with a central Li₂O₂ four‐membered ring, the oxygen atoms of which are connected by ‐SiMe₂‐ bridges with the cuprate fragment > CH–Cu–CH₂‐.     

Investigations of Structure and Stability of the Tetrachlorinedecaoxide Anion Complex (TCDO)

Raman spectroscopic and ³⁵Cl‐NMR scans of Hydro‐Xan®, a preparation containing the biocatalytically effective Tetrachlorinedecaoxide anion (TCDO), are described. The spectroscopic analyses showed that HydroXan® does not contain chlorite initially used in the preparation anymore. Furthermore, a structure of four equal chlorate‐like ClO₃‐groups was indicated for TCDO by the scans. Such a structure is supported by the long‐term stability of HydroXan® found at tests over 267 days.     

Diacetonalkohol‐Komplexe von Lanthanoid‐Trichloriden. Die Kristallstrukturen von [LnCl3(DAA)2] mit Ln = Sm und Eu

Diacetone Alcohol Complexes of Lanthanide Trichlorides. Crystal Structures of [LnCl₃(DAA)₂] with Ln = Sm and Eu The diacetone alcohol complexes [LnCl₃(DAA)₂] with Ln = samarium ( 1 ) and europium ( 2 ) are obtained from the waterfree metal trichlorides with excess diacetone alcohol (4‐hydroxy‐4‐methyl‐2‐pentanone = DAA) forming colourless ( 1 ) and pale yellow crystals ( 2 ), respectively, which are characterized by crystal structure determinations. The europium compound 2 is additionally described by its vibrational spectra (IR, Raman). 1 and 2 crystallize isotypically with one another. The metal atoms of the molecular complex units are unusually coordinated in a distorted pentagonal‐bipyramdial fashion by the three chlorine atoms and by the two alcoholic oxygen atoms of the DAA molecules in the equatorial plane. The apical positions are occupied by the carbonyl oxygen atoms of the chelating DAA molecules. The complex units [LnCl₃(DAA)₂] are associated along [100] by bifurcated —OH···Cl···HO— bridges to form chains. 1 : Space group P2₁, Z = 2, lattice dimensions at —80 °C: : a = 710.2(1), b = 1617.6(2), c = 827.3(1) pm; β = 106.36(1)°; R₁ = 0.026. 2 : Space group P2₁, Z = 2, lattice dimensions at —80 °C: a = 709.7(1), b = 1614.5(2), c = 825.7(1) pm; β = 106.40(1)°; R₁ = 0.0303.     

Determination of Fluorescence Cross‐Sections of Biological Aerosols

Biological aerosols like pollen or bacteria can be differentiated from non‐biological aerosols as dust by fluorescence. Several organic substances contained in biological particles emit fluorescence light if they are illuminated with ultraviolet light. An instrument has been developed which generates aerosols of individual bacteria, illuminates them with light in the range of wavelengths from 220 to 570 nm and detects the spectra of fluorescence. The instrument has been tested on different species of bacteria showing that their fluorescence spectra are different.     

Hydrogen‐Bonding in Cyclic 2‐(3‐Oxo‐3‐phenylpropyl)‐Substituted 1,3‐Diketones: 17O‐NMR Spectra and X‐Ray Structure Determination

Structures of cyclic 2‐(3‐oxo‐3‐phenylpropyl)‐substituted 1,3‐diketones 4a – c were determined by ¹⁷O‐NMR spectroscopy and X‐ray crystallography. In CDCl₃ solution, compounds 4a – c form an eight‐membered‐ring with intramolecular H‐bonding between the enolic OH and the carbonyl O(11)‐atom of the phenylpropyl group, as demonstrated by increased shielding of specifically labeled 4a – c in the ¹⁷O‐NMR spectra (Δδ(¹⁷O(11))=36 ppm). In solid state, intermolecular H‐bonding was observed instead of intramolecular H‐bonding, as evidenced by the X‐ray crystal‐structure analysis of compound 4b . Crystals of compound 4b at 293 K are monoclinic with a=11.7927 (12) Å, b=13.6230 (14) Å, c=9.8900 (10) Å, β=107.192 (2)°, and the space group is P2₁/c with Z=4 (refinement to R=0.0557 on 2154 independent reflections).     

One‐Pot,Asymmetric and Diastereoselective Four‐Component Synthesis of Polyfunctional (Z)‐Alkenyl Methyl Sulfones with Three Stereogenic Centers

The reaction of 1‐(trimethylsilyloxy)cyclopentene ( 9 ) with (±)‐1,3,5‐triisopropyl‐2‐(1‐(RS)‐{[(1E)‐2‐methylpenta‐1,3‐dienyl]oxy}ethyl)benzene ((±)‐ 4a ) in SO₂/CH₂Cl₂ containing (CF₃SO₂)₂NH, followed by treatment with Bu₄NF and MeI gave a 3.0 : 1 mixture of (±)‐(2RS)‐2{(1RS,2Z,4SR)‐2‐methyl‐4‐(methylsulfonyl)‐1‐[(RS)‐1‐(2,4,6‐triisopropylphenyl)ethoxy]pent‐2‐en‐1‐yl}cyclopentanone ((±)‐ 10 ) and (±)‐(2RS)‐2‐{(1RS,2Z)‐2‐methyl‐4‐[(SR)‐methylsulfonyl]‐1‐[(SR)‐1‐(2,4,6‐triisopropylphenyl)ethoxy]pent‐2‐en‐1‐yl}cyclopentanone ((±)‐ 11 ). Similarly, enantiomerically pure dienyl ether (−)‐(1S)‐ 4a reacted with 1‐(trimethylsilyloxy)cyclohexene ( 12 ) to give a 14.1 : 1 mixture of (−)‐(2S)‐2‐{(1S,2Z,4R)‐2‐methyl‐4‐(methylsulfonyl)‐1‐[(S)‐1‐(2,4,6‐triisopropylphenyl)ethoxy]pent‐2‐enyl}cyclohexanone ((−)‐ 13a ) and its diastereoisomer 14a with (1S,2R,4R) or (1R,2S,4S) configuration. Structures of (±)‐ 10 , (±)‐ 11 , and (−)‐ 13a were established by single‐crystal X‐ray crystallography. Poor diastereoselectivities were observed with the (E,E)‐2‐methylpenta‐1,3‐diene‐1‐ylethers (+)‐ 4b and (−)‐ 4c bearing ( 1 S )‐1‐phenylethyl and (1S)‐1‐(pentafluorophenyl)ethyl groups instead of the Greene's auxiliary ((1S)‐(2,4,6‐triisopropylphenyl)ethyl group). The results demonstrate that high α/β‐syn and asymmetric induction (due to the chiral auxiliary) can be obtained in the four‐component syntheses of the β‐alkoxy ketones. The method generates enantiomerically pure polyfunctional methyl sulfones bearing three chiral centers on C‐atoms and one (Z)‐alkene moiety.     

Characterization of the Element Distribution Within TiN Coatings with SIMS

 The distribution of the relevant elements within TiN coatings, made with two different physical deposition methods as the conventional dc vacuum arc method and the filtered high current pulsed arc method (Φ-HCA) are characterized and finally compared. Despite the rougher surface of the dc-arc produced TiN layer, which is due to accumulated droplets, there is no evidence of different stoechiometric composition of Ti and N on the surface. The interface of the dc-arc produced TiN layer (600 nm) is 10 times wider than the one made with the new filtered high current pulsed arc method (60 nm). However the TiN layer made by Φ-HCA shows an inhomogeneous distribution of aluminum and chlorine in the vertical direction, whereas the dc-arc sample is homogeneous. Furthermore, the TiN layer made by Φ-HCA shows vertically an obvious local maximum of chlorine at a depth of about 130 nm. This vertical local maximum has an homogeneous distribution in horizontal direction, which means that a thin, chlorine enriched layer has been incorporated inside the TiN layer. Nevertheless, quantification by SIMS shows that aluminum as well as chlorine concentrations of both samples are too low to influence any TiN properties. Received January 3, 2000. Revision April 4, 2000.     

[2-(N,N-Dimethylaminomethyl)ferrocenyl] as a ligand towards mercury

The diorganomercurial bis[2-(N,N-dimethylaminomethyl)ferrocenyl]mercury(II), (FcN)₂Hg (3), can be obtained by the symmetrisation of the heteroleptic (FcN)HgCl (2) with Na₂S₂O₃ or in the transmetallation reaction of 2 with (FcN)Li. By crystallisation only the crystals of rac-(FcN)₂Hg were obtained. X-ray diffraction analysis revealed linear coordinated mercury atom with two η¹-bonded FcN ligands. Additionally, weak chelate interactions exist between mercury and nitrogen atoms of the ---CH₂NMe₂ side chains. According to the ¹H-NMR findings, these interactions are not preserved in solution. Diorganomercurial 3 appears in solution as a mixture of two diastereomers with rac/meso-(FcN)₂Hg ratio of 1:1. This diastereomeric ratio in solution remains constant within a wide temperature range and in different solvents. The NMR spectroscopic data of the heteroleptic organomercurials [(FcN)HgCl]₂·H₂O (1) and (FcN)HgCl (2) indicate the chelate-free structure of this compounds in solution within the studied temperature interval (−80 to 90 °C).     

The deviating behavior of thiols in nucleophilic trapping reactions of chromiumcarbonyl phenyl complex substituted propargyl cation

The (phenyl)Cr(CO)₃-complex substituted propargyl cation 4 significantly deviates in the chemoselectivity of the nucleophilic attack of thiols from the previously reported planar chiral ortho-substituted arene complexes and furnishes allenyl thioethers 5. This peculiar behavior can be rationalized assuming a subsequent base catalyzed propargyl–allenyl isomerization in acidic medium (!). An X-ray structure analysis of allenyl thioether 5c recrystallized from acetonitrile over weeks reveals that the [2+2] cyclodimer 10 has been formed. Thiolate adds to 5c to give a single diastereomer of the allyl compound 15 in good yield.     

Determination of trimethylselenonium iodide, selenomethionine, selenious acid, and selenic acid using high-performance liquid chromatography with on-line detection by inductively coupled plasma mass spectrometry or flame atomic absorption spectrometry

An analytical method has been developed for the determination of selenious acid, selenic acid, trimethylselenonium ion, and selenomethionine. The four selenium compounds were separated by HPLC on a column (25 cm×4 mm I.D.) of the anion-exchanger ESA Anion III with a mobile phase (1.5 ml/min) of 0.0055 M ammonium citrate (pH 5.5). Detection was carried out using an on-line inductively coupled plasma mass spectrometer (ICP-MS) or a flame atomic absorption spectrometer (FAAS) as the selenium-specific detector. The chromatographic parameters and the chemical factors affecting the separation of the selenium species were optimized. The four selenium compounds could be separated within 8 minutes. The detection limits of the coupled HPLC–FAAS system were approximately 1 mg Se/l for each compound (100 μl injection), estimated as three times the base-line noise of the chromatograms. More powerful selenium detection was achieved with an ICP-MS. Selenium was measured at m/z 78. To increase the nebulization efficiency, the Meinhard concentric glass nebulizer was replaced by an ultrasonic nebulizer. The ICP-MS signal intensity was increased with the ultrasonic nebulization by a factor of 7 times for selenious acid and 24 to 31 times for trimethylselenonium ion, selenomethionine, and selenic acid compared to that with the Meinhard nebulization. The detection limits achieved by the HPLC–ICP-MS with the ultrasonic nebulization were 0.08 μg Se/l for trimethylselenonium ion, 0.34 μg Se/l for selenious acid, 0.18 μg Se/l for selenomethionine, and 0.07 μg Se/l for selenic acid, respectively.