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Diamagnetic Technetium(V) complexes of general formulae [TcNX 2 (Ph 3 Y) 2 ] and [TcNX 3 (Me 2 PhP) 3 ] (X = Cl, Br; Y = P, As) were prepared starting from TcNCl 4 − and TcNBr 4 − , respectively and were characterized. Ligand exchange rates with diethyldithiocarbamate, et 2 dtc − and N-(N″-morpholinylthiocarbonyl)benzamidinate, morphtcb − , were determined.

Die Bildung von Anilin aus Stickstoff bei der Thermolyse von Diphenyltitanocen (1) und im Reaktionssystem (C5H5)2TiCl2 (3) + Mg + o-Bromfluorbenzol (4) + N2 verlauft uber die Reaktion von N2 mit einem intermediaren Titan-Dehydrobenzol-Komplex (2). Das ergibt sich aus der Isomerenverteilung von Toluidinen, die aus N2 und Ditolyltitanocenen erhalten wurden, aus der Bildung von [2-D1]Anilin bei Hydrolyse des Systems 3 + Mg + 4 + N2 mit D2O sowie aus Stickstoffisotopen-Fraktionierungen in den Reaktionsprodukten mit naturlicher 15N-Haufigkeit. The Reaction of Dinitrogen with Benzyne in the Coordination Sphere of Titanium The formation of aniline from dinitrogen during the thermolysis of diphenyltitanocene (1) and in the system (C5H5)2TiCl2 (3) + Mg + o-bromofluorobenzene (4) + N2 has been found to proceed via N2 reaction with intermediate Ti-benzyne complex (2). This is indicated by the isomeric composition of toluidines obtained from N2 and ditolyltitanocenes, the formation of [2-D1]aniline in the system 3 + Mg + 4 + N2 on hydrolysis with D2O and by nitrogen isotope fractionations at natural 15N-abundance in the reaction products.

The d 5 -‘low-spin’ Tc(II) complexes tribromonitrosyl-bis(dimethylphenylphosphine)technetium(II) and tribromo-thionitrosyl-bis(dimethylphenylphosphine)technetium(II) were prepared by ligand exchange starting from the analogous chloro compounds. The complexes were characterized chemically and IR, UVVis and EPR spectroscopically. In the room temperature EPR spectra a well-resolved 99 Tc hyperfine splitting is observed inidicating a ground state of the unpaired electron which is well separated from the other orbit states. The general features of the spectra at low temperatures are characteristic for an axially symmetric spin Hamiltonian. Analysis of the 99 Tc and 31 P hfs (hfs = hyperfine splittings) shows a marked covalency of the Tcligand bonds. A comparison is given between the chloro and bromo, as well as between the nitrosyl and thionitrosyl complexes.

The d 5 low-spin Tc(II) complex trichloro-nitrosyl-bis(dimethylphenyl-phosphine)technetium(II) was studied by EPR at 295 ≥ T ≥ 27.2 K. In the room-temperature spectrum well-resolved 99 Tc hyperfine splitting is observed indicating a ground state for the unpaired electron which is well separated from other orbital states. At low temperatures the spectrum can be fitted by an axial spin Hamiltonian. The analysis of the 99 Tc hyperfine splitting shows remarkable covalent interactions with the “in-plane” ligands. The 31 P superhyperfine splitting observed was used to get information about the overall spin density distribution in the molecular orbital of the unpaired electron.

Die Titelverbindung Tc15NCl2(Me2PhP)3I wurde durch Reaktion von mer-TcCl3(Me2PhP)3 mit Na15N3 dargestellt und ihre Kristall- und Molekulstruktur durch Rontgenstrukturanalyse ermittelt. Die Kristalle sind orthorhombisch, Raumgruppe Pbca, mit a = 16,663(1), b = 19,219(1), c = 16,769(1) A und Z = 8. Das Technetiumatom hat verzerrt oktaedrische Koordinationsgeometrie mit meridionaler Anordnung der Phosphine. Infolge des ausgepragten trans-Effektes des Nitridoliganden ist der TcCl-Bindungsabstand in trans-Stellung zum Nitridoliganden um 0,22 A groser als jener, der sich in trans-Stellung zum Phosphinliganden befindet. Crystal and Molecular Structure of 15N-Nitridodichlorotris(dimethylphenylphenylphosphine)technetium(V) The title compound Tc15NCl2(Me2PhP)3I has been prepared by the reaction of mer-TcCl3(Me2PhP)3 with Na15N3. The crystal structure of I has been determined by single crystal X-ray diffraction methods at room temperature. Crystals are orthorhombic, space group Pbca, with a = 16.663(1), b = 19.219(1), c = 16.769(1) A and Z = 8. The technetium atom is six-coor-dinate. The coordination geometry is that of a distorted octahedron with 3 phosphine ligands in meridional positions. The strong trans influence of the nitrido ligand has been noted. The TcCl length trans to N is 2.665(1) A while those trans to P is 2.441(1) A.

Technetiumpentacarbonylbromid reagiert mit π-Akzeptor-Liganden L, wie Phosphinen, Pyridinderivaten und Isocyaniden zu den Disubstitutionsverbindungen Tc(CO)3BrL2. Die Stereochemie der gebildeten Komplexe wurde durch IR- und 1H-NMR-Spektroskopie ermittelt. Der Einflus der Liganden auf Lage und Halbwertsbreite der 99Tc-NMR-Signale wird diskutiert. Technetium(I) Complexes Tc(CO)3BrL2 (L = Phosphine, Pyridine, Isocyanide) Technetium Pentacarbonyl Bromide reacts with π-acceptor ligands L (L = Phosphine, Pyridine, Isocyanide) to form disubstituted compounds of the type Tc(CO)3BrL2. The stereochemistry of the complexes was established by infrared and 1H-NMR measurement. Chemical shifts and the half-widths of the 99Tc-NMR signals are discussed.

Cubic boron nitride is synthesized using Mg3N2 as a catalyst at a pressure of 6.5 GPa in the temperature range 1600

Mit N,N′-Bis-(Furfur-2-al)athylendiimin (A) werden Chelate der d10-Ionen Cd++, Zn++, Cu+, Ag+ vom Typ MeA2 als Perchlorate bzw. Nitrate dargestellt. Das orangefarbene Kupfer(I)-Chelat ist in wasriger Losung bemerkenswert stabil gegen Disproportionierung und Hydrolyse. Die Brutto-Zerfallkonstanten fur die Hydrolyse von A und MeA2 werden durch Auswertung der Saureverbrauchskurven in 7,5 Gew.-% Methanol bei pH 8 und 20° ermittelt. Die Reaktionen verlaufen nach 1. Ordnung. Chelate compounds of the d10 ions Cd++, Zn++, Cu+ and Ag+ with N,N′-bis-(furfur-2-al)ethylenediimine (A) have been prepared. They are of the type MeA2 and were isolated as perchlorates or nitrates. The orange-coloured copper(I) chelate is comparatively stable against oxidation and hydrolytic cleavage of the ligand. Rate constants for the first-order overall hydrolytic decomposition of A and MeA2 at 20° and pH 8 in 7.5 weight-% methanol have been determined by pH-stat recording of the acid being consumed.

Es wird uber chemische, elektronenspektroskopische und ESR-spektroskopische Ergebnisse an neutralen Diselenocarbamatchelaten von GaIII, InIII, TlIII, AuIII, RhIII, FeIII, CrIII, MnIII, CoIII (Tris-Komplexe), NiII, CuII, PtII, PdII (Bis-Komplexe) und UIV (Tetrakiskomplex) berichtet. OsIV und RuIV werden vom Liganden reduziert, und die dreiwertigen Ionen bilden Tris-Chelate. Die Ergebnisse werden mit Aussagen uber die Ligandeneigenschaften von Dithiocarbamaten verglichen. New synthesized chelates of Diselenocarbamates with the tripositive forms, of Ga, In, Tl, Au, Rh, Fe, Cr, Mn and Co (Tris-complexes), the dipositive of Ni, Cu, Pt, Pd (Bis-complexes) and tetravalent U (Tetrakis-complex) have been characterized chemically, spectroscopically (UV, vis) and EPR spectroscopically. OsIV and RuIV are reduced by the ligand and form Tris-chelates of the tripositive ions

N,N′-Bis-(Pyridin-2-al)athylendiimin I und N,N-Bis-(Chinolin-2-al)-athylendiimin III liefern mit den Metallionen CuI, AgI und CdII kristalline 1:1-Chelate, wogegen von I mit NiII, FeII und HgII 1:2-Chelate isoliert wurden. III bildet mit CuII und FeII 1:2-Chelate, wobei die Komplexe des halftig hydrolysierten Liganden erhalten werden. Die CuI- und die FeII-Chelate sind intensiv gefarbt. Die Hydrolysegeschwindigkeit der Koordinierten Liganden wurde pH-stat titrimetrisch bei 200 in 7.5 bzw. 27 Gew.-% Methanol gemessen, die der FeII- und der CuI-Chelate spektralphotometrisch in 50 Gew.-% Methanol und Mineralsaurezusatz. N.N′-Bis-(pyridine-2-al-)ethylenediimine I and N.N′-bis-(quinoline-2-al)ethylene-diimine III yield cristalline 1:1 chelates with Cu1. Ag1 and CdII whereas 1:2 chelates have been isolated from I with NiII, FeII and HgII, III forms 1:2 chelates with CuII and FeII, yielding complexes of the partly hydrolized ligand. Rate constants for the pseudo first-order overall hydrolytic cleavage of the free and co-ordinated ligands have been determined by pH-stat and spectrophotometric measurements.

Die Existenz von Silber(II)- und Gold(II)-bis-(dialkyl-diselenocarbamaten) wird ESR-spektroskopisch in Losung bzw. Ag(II) auch in Pulvern nachgewiesen. Die ESR-Pulverspektren der Ag(II)-Chelate zeigen, das sowohl der Ag-Hyperfeinstrukturtensor wie auch der g-Tensor rhombische Symmetrie besitzen. Der grose Beitrag der Spin-Bahn-Wechselwirkung in den Selenatomen zum g-Tensor und die starke π-Kovalenz der d9-Metall-Se-Bindung verursachen ein Absinken der g-Werte in die Nahe des g-Wertes des freien Elektrons. Die 77Se-Ligandenhyperfeinstruktur wurde zum Abschatzen des Kovalenzgrades der Grundzustands-σ-Bindung benutzt. Der in der Reihe Cu. Ag Au stark anwachsende Beitrag der isotropen Hyperfeinstruktur-Wechselwirkung weist auf ansteigende Beimischung von s-Orbitalen in das einfach besetzte Grundzustands-MO hin. The existence of silver(II) and gold(II) bis-(dialkyl-diselenocarbamate) has been proved EPR-spectroscopically (solution and – Ag(II) – powder spectra). In the EPR powder spectra for the silver (II) chelates the Ag-hfs-tensor and also the g-tensor exhibit rhombic symmetry. The important contribution of the spin-orbit interaction in the selenium atoms to the g-tensor and the strong π-covalence of the d9-metal-Se bond cause low g-values which are near to the free-electron g-value. The 77Se-ligand-hfs is used to estimate the degree of covalency of the groundstate σ-bond. In the series Cu, Ag, An the contribution of the isotropic hyperfine interaction increases strongly in agreement with an increased admixture of s-orbitals to the groundstate MO of the unpaired electron.

Es wurden die 1:1-Chelate von N,N′-Bis-(pyridin-2-al)athylendiimin (PAen) mit Sm(III), Eu(III) und Tb(III) als Nitrate dargestellt. Aus den IR-Spektren folgt, das sowohl der Pyridin- als auch der Azomethinstickstoff und die Nitratgruppen im festen Zustand koordinieren. Diese Aussagen werden durch die Aufnahme der Fluoreszenzspektren an den festen Chelaten und Vergleich mit den ebenfalls untersuchten 1:2-Phenanthrolin-(Phen) bzw. α,α′-Dipyridyl(Dip) Komplexen sowie durch die Temperaturabhangigkeit der Fluoreszenz erhartet.

During the last decade, five patients with laser injuries were examined at the University of Munich Eye Clinic, in addition to one laser-injury patient at the University of Erlangen Eye Clinic. From a review of these cases, it is possible to gain an insight into factors that led to the eye injuries and to predict the clinical sequelae of laser retinal injury. A possible means of treatment, using an ophthalmic Q-switched Nd:YAG laser, is suggested for some types of retinal injury involving vitreal hemorrhage. Language: en

Etude sur la cooperation des bibliothecaires au sein d'un groupe de travail sur les classifications. Remarques sur l'environnement du plan de travail de l'Association des utilisateurs des classifications a Ratisbonne. Etude comparative avec la classification de la Library of Congress

Diamagnetic Technetium(V) complexes of general formulae [TcNX 2 (Ph 3 Y) 2 ] and [TcNX 3 (Me 2 PhP) 3 ] (X = Cl, Br; Y = P, As) were prepared starting from TcNCl 4 − and TcNBr 4 − , respectively and were characterized. Ligand exchange rates with diethyldithiocarbamate, et 2 dtc − and N-(N″-morpholinylthiocarbonyl)benzamidinate, morphtcb − , were determined.

Polyclonal, monospecific antibodies were produced against the two subunits (Mr 62 000, and Mr 31 000), isolated from the membrane-bound hydrogenase of Alcaligenes eutrophus H16. The antibodies (IgG fractions) were purified from crude sera by Protein A-Sepharose CL-4B chromatography. By double immunodif usion assays and tandem-crossed immunoelectrophoresis the large and the small subunit were demonstrated not to be immunologically related. Immunological comparison of these subunits with the four non-identical subunits (Mr 63 000, 56 000, 30 000 and 26 000) of the NAD-linked, soluble hydrogenase from A. eutrophus H16 showed that the subunits of the membrane-bound hydrogenase did not cross-react with any of the antibodies raised against the four subunits of the NAD-linked enzyme and that, vice versa, none of these four subunits cross-reacted with antibodies raised against the two subunits of the membrane-bound hydrogenase. This means that A. eutrophus H16 contains altogether six non-identical immunologically unrelated hydrogenase polypeptides. The membrane-bound hydrogenases were isolated and purified from various aerobic H2-oxidizing bacteria: A. eutrophus H16, A. eutrophus type strain, A. eutrophus CH34, A. eutrophus Z1, A. hydrogenophilus, Paracoccus denitrificans and strain Cd2/01. All These proteins resembled each other and each consisted of two non-identical polypeptides. A complete separation of these subunits was achieved at high-yield by preparative FPLC gel filtration of three Superose 12 columns connected in series, using SDS and DTT-containing sodium phosphate buffer (pH 7.0). The small subunits of these enzymes turned out to be immunologically closely related to each other; they were either identical or almost identical. The large subunits were also related, but less pronounced. Only the large subunits from Z1 and type strain reacted fully identical with the H16 subunit. Of the two isolated, homogeneous subunits of the membrane-bound hydrogenase from A. eutrophus H16, the amino acid compositions and the NH2-terminal sequences have been determined. The results confirmed the diversity of the large and the small subunit. Furthermore, for comparison also the NH2-terminal sequences of the two subunits from the hydrogenase of A. eutrophus CH34 have been analysed.

The dinitrogen complex (I) is a suitable starting compound for the synthesis of mixed ligand complexes of Tc in its lower oxidation states.

Die folgenden Uberlegungen zu Klassifikation und Klassifikationsregistern sind nicht als Prasentation von Losungen gedacht, sondern vielmehr als Aufzeigen von Problemen und damit als Bitte um Diskussion und Erfahrungsaustausch.

Es wird uber chemische, elektronenspektroskopische und ESR-spektroskopische Ergebnisse an neutralen Diselenocarbamatchelaten von GaIII, InIII, TlIII, AuIII, RhIII, FeIII, CrIII, MnIII, CoIII (Tris-Komplexe), NiII, CuII, PtII, PdII (Bis-Komplexe) und UIV (Tetrakiskomplex) berichtet. OsIV und RuIV werden vom Liganden reduziert, und die dreiwertigen Ionen bilden Tris-Chelate. Die Ergebnisse werden mit Aussagen uber die Ligandeneigenschaften von Dithiocarbamaten verglichen. New synthesized chelates of Diselenocarbamates with the tripositive forms, of Ga, In, Tl, Au, Rh, Fe, Cr, Mn and Co (Tris-complexes), the dipositive of Ni, Cu, Pt, Pd (Bis-complexes) and tetravalent U (Tetrakis-complex) have been characterized chemically, spectroscopically (UV, vis) and EPR spectroscopically. OsIV and RuIV are reduced by the ligand and form Tris-chelates of the tripositive ions

The potential role of inorganic polyphosphates in the response of algal cells to osmotic stress was investigated. We show that changes in polyphosphate metabolism of algae induced by osmotic stress can be easily determined by measuring the metachromatic shift of toluidine blue produced by polyphosphate and by analysing the size of the extracted polyphosphate on urea/polyacrylamide gels. The amount and size of polyphosphate were found to differ considerably among different algal species. It is demonstrated that the alga Phaeodactylum tricornutum responds to hyperosmotic stress with a marked elongation of polyphosphate molecules and a decrease in the total amount of extractable polyphosphate, while exposure to hypoosmotic stress results in an increase in soluble shorter-chain polyphosphates and a rise in total polyphosphate content.

We have studied the kinetics of the chemical reaction between Mg and B by differential thermal analysis. There are two exothermal peaks observed at 500 and 650 °C. We speculate that the first exothermal peak is mainly related to the chemical reaction between Mg and oxygen, forming MgO. The second exothermal peak, which coincides with the melting point of Mg, clearly indicates the chemical reaction between Mg and B. The effect of synthesis conditions and defects on the transport property of MgB2 has been investigated. A correlation between the microstrain, the lattice parameters, and the Mg concentration were observed and are discussed.