Organotransition-Metal Metallacarboranes. 46. Multidecker Sandwiches of the Cobalt Group Metals(,)(1)

The double-decker sandwich complex CpIr(2,3-Et(2)C(2)B(4)H(4)) (1a) was prepared via deprotonation of nido-2,3-Et(2)C(2)B(4)H(6) to its mono- or dianion and reaction with (CpIrCl(2))(2) in THF and isolated as a colorless air-stable solid; the B(4)-chloro derivative 1b was also obtained. Decapitation of 1a and 1b with TMEDA afforded colorless nido-CpIr(2,3-Et(2)C(2)B(3)H(5)) (2a) and its 4-chloro derivative 2b. Chlorination of 1a by Cl(2) or N-chlorosuccinimide gave the symmetrical species CpIr(2,3-Et(2)C(2)B(4)H(3)-5-Cl) (1c), which was decapped to yield nido-CpIr(2,3-Et(2)C(2)B(3)H(4)-5-Cl) (2c). The triple-decker complexes CpIr(2,3-Et(2)C(2)B(3)H(2)-4[6]-Cl)IrCp (3), an orange solid, and dark green CpIr(2,3-Et(2)C(2)B(3)H(2)-4[6]-Cl)CoCp (5) were prepared from 2a and nido-CpCo(2,3-Et(2)C(2)B(3)H(5)) (4a), respectively, by deprotonation and reaction with (CpIrCl(2))(2) in THF. Reaction of the 2c(-) anion with Rh(MeCN)(3)Cl(3) gave the dark green tetradecker complex [CpIr(Et(2)C(2)B(3)H(2)-5-Cl)](2)RhH (6). In an attempt to prepare a heterotrimetallic Co-Rh-Ir tetradecker sandwich, a three-way reaction involving the deprotonated anions derived from CpCo(2,3-Et(2)C(2)B(3)H(4)-5-Cl) (4b) and 2c with Rh(MeCN)(3)Cl(3) was conducted. The desired species CpCo(Et(2)C(2)B(3)H(2)Cl)RhH(Et(2)C(2)B(3)H(2)Cl)IrCp (7) and the tetradeckers [CpCo(Et(2)C(2)B(3)H(2)Cl)](2)RhH (8) and 6 were isolated in small quantities from the product mixture; many other apparent triple-decker and tetradecker products were detected via mass spectroscopy but were not characterized. All new compounds were isolated via column or plate chromatography and characterized via NMR, UV-visible, and mass spectroscopy and by X-ray crystal structure determinations of 1a and 3. Crystal data for 1a: space group C2/c; a = 28.890(5) ?, b = 8.511(2) ?, c = 15.698(4) ?, beta = 107.61(2) degrees; Z = 8; R = 0.049 for 1404 independent reflections having I > 3sigma(I). Crystal data for 3: space group P2(1)/c; a = 11.775(4) ?, b = 15.546(5) ?, c = 15.500(5) ?, beta = 103.16(3) degrees; Z = 4; R = 0.066 for 2635 independent reflections having I > 3sigma(I).     

Synthesis of a Sialyl Lewis x Mimic with Fixed Carboxylic Acid Group: Chemical Approach toward the Elucidation of the Bioactive Conformation of Sialyl Lewis x

The relation of the solution and bioactive conformation of sialyl Lewis x (sLe(x)) has been addressed by chemical means. To mimic the preferred solution conformation of sLe(x) 1, the more rigid analog 2 has been designed and synthesized. The sialic acid residue of 1 was replaced by a carboxylic acid function which is fixed in the equatorial position of a six membered ring acetal fused to galactose. Due to entropic considerations, an increased biological activity could be expected if the preferred solution conformation and bound form of sLe(x) were similar. Since mimic 2 was found to be inactive in an E-selectin binding assay, the bound form of sLe(x) most probably differs from the prevailing solution conformation.     

Imaging of the formerly bonded area of individual fibre to fibre joints with SEM and AFM

Besides the determination of the force and the energy needed to break individual fibre to fibre joints, the investigation of the formerly bonded area (FBA) is of essential importance to learn more about the failure mechanisms of fibre–fibre bonds in general. In this study the surfaces of paper fibres and the FBA of fibre–fibre joints after the determination of the breaking force as well as the bonding energy were analysed by means of low voltage scanning electron microscopy and atomic force microscopy. A comparison between the contact zone of fibres broken at different loading rates as well as under cyclic loading showed that there seems to be no significant difference in the appearance of the FBA in these cases. Only minor delamination of the cell wall could be found in the bonding zone, which indicates no mechanical interlocking of fibrils in the bonding zone. Furthermore, it is shown that some glues used for specimen preparation of fibre–fibre bond strength measurement are forming a glue film on the fiber surface and migrate into the bonding region.     

AES investigations of the iron surface composition after laser irradiation under atmospheric conditions

The laser induced modification of iron surfaces with atmospheric species was investigated by means of Auger electron spectroscopy (AES) and scanning electron microscopy (SEM). Different laser systems were used for irradiating iron samples in a wide range of the laser processing parameters up to small foci and ultra short pulses.A nitriding of iron connected with an oxidation of the near surface region was observed in the wavelength range between 193 nm and 10.6 m using large foci (0.1 cm²) and short pulses (10...1400ns). In case of small foci (7·10^–6cm²) with ns-pulses (50 ns) an enrichment of the iron melt with nitrogen and an advanced oxidation of the surrounding area of the laser spot were detected. When using shorter pulses (200 fs, 40 ps) no indications for a nitriding were found.     

Activation-analysis investigation of the behaviour of biological trace elements during wound healing: The roles of calcium and iron

Summary Instrumental neutron-activation analysis was used for the determination of Ca, Cr, Fe, Co, Ni, Zn, Mo, Ag, Sb, and Hg. Blood and tissue samples of 70 mg each were analysed and, from these, changes in the concentrations of calcium, iron, and zinc in affected tissue were established. In this article the results of the behaviour of calcium and iron are reported. The calcium concentration of the fracture haematoma blood (FHB) is about 20 times higher than that of arterial or venous blood (rabbits). The level and the change with time of the calcium concentration in FHB-deposits (rabbits) can be explained by the participation of calcium in the haemolysis of the erythrocytes of the FHB which has been injected for the formation of the deposits. The behaviour of the iron in the FHB-deposits is in agreement with this explanation. The change in calcium concentration in the crust of punch-hole wounds in the skin (rats) can be attributed to the mobilization of calcium for fibrin formation. As a reason for the level and the change with time of the iron concentration in the tissue in the area of fascia and muscle incision wounds (rabbits) the participation of iron in the formation of collagen is discussed. From comparison of the behavoiur of the iron in the FHB-deposits with that in the area of incision wounds it follows that iron enrichments in the area of a complication-free wound are not predominantly caused by a wound haematoma.

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Zusammenfassung Die Untersuchungen erfolgten mit Hilfe der instrumentellen Neutronenaktivierungsanalyse. Das Verfahren war für die Erfassung der Gehalte an Ca, Cr, Fe, Co, Ni, Zn, Mo, Ag, Sb und Hg ausgelegt. Es wurden Blut bzw. Gewebeproben von jeweils etwa 70 mg analysiert und dabei Änderungen der Calcium-, Eisen- und Zinkgehalte des betroffenen Gewebes festgestellt. In diesem Artikel wird über das Verhalten des Calciums und Eisens berichtet. Der Calciumgehalt des Frakturhämatombluts (FHB) ist etwa 20mal höher als der von arteriellem oder venösem Blut (Kaninchen). Höhe und zeitlicher Verlauf der Calciumgehalte von FHB-Depots (Kaninchen) lassen sich mit der Beteiligung des Calciums an der Hämolyse der Erythrozyten des FHB erklären, das zur Bildung der Depots injiziert wurde. Das Verhalten des Eisens in den FHB-Depots stimmt mit dieser Erklärung überein. Der Verlauf der Calciumgehalte des Schorfes von Hautstanzwunden (Ratten) kann auf die Mobilisierung von Calcium für die Fibrinbildung zurückgeführt werden. Als Ursache für Höhe und zeitlichen Verlauf der Eisengehalte des Gewebes im Bereich von Faszie- und Muskelschnittwunden (Kaninchen) wird die Beteiligung des Eisens an der Kollagenbildung diskutiert. Aus dem Vergleich des Verhaltens des Eisens in FHB-Depots und im Bereich von Schnittwunden folgt, daß die Eisenanreicherungen im Bereich einer komplikationslosen Schnittwunde nicht vorwiegend durch ein Wundhämatom bedingt sind.

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Auszug aus der Dissertation des Herrn Danilo Boani, Technische Universität München. This work was supported by the Bundesministerium für Forschung und Technologie and the Fonds der Chemischen Industrie, and the paper was presented at the International Symposium on Microchemical Techniques, Davos, May 1977.     

Unterscheidung einiger isomerer Kohlenwasserstoffe durch Registrierung der metastabilen Ionen im Massenspektrometer

Some isomeric hydrocarbons with nearly identical mass spectra show significant differences in the spectra of neutral fragments, these spectra being determined by measuring the decompositions of metastable ions.     

The Adamantane Rearrangement of 1,2endo-Trimethylenenorbornane. Preliminary communication

1,2endo-Trimethylenenorbornane (1) in the presence of aluminium bromide in carbon disulfide at ?60° isomerizes at a much higher rate than its 2exo-isomer 2 to 2endo, 6endo-trimethylenenorbornane (3) as the sole product. By consequence, the hydrocarbon 2 being the next intermediate in the sequence of the adamantane rearrangement of 1 seems to be very unlikely.     

The electron impact fragmentation of 3- and 4-styrylpyridazine

The electron impact mass spectrometric fragmentation of trans-3- and trans-4-styrylpyridazine is reported in detail, including a comparison with other aza-stilbenes. With regard to a distinction between the two isomeric styrylpyridazines, the intensity ratio of the M⁺ and [M-1]⁺ ions, the general degree of fragmentation and the elimination pathways of nitrogen proved to be most characteristic.