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111.
112.
Phosphoraneiminato Cluster of Iron. The Crystal Structures of [FeCl(NPEt3)]4, [Fe(C=C–SiMe3)(NPEt3)]4, and [Fe3Cl4{NP(NMe2)3}3] The reaction of iron dichloride with the silylated phosphaneimine Me3SiNPEt3 in the presence of potassium fluoride at 165 ?C leads to the phosphoraneiminato complex [FeCl(NPEt3)]4 ( 1 ). Compound 1 forms black, moisture and oxygen sensitive crystals. According to the crystal structure analysis 1 has a heterocubane structure, in which the iron and the nitrogen atoms of the NPEt3– groups occupy the corners of a distorted cube and form Fe–N–Fe bond angles of 83.1? and N–Fe–N angles of 96.5?. This results in significantly short Fe…Fe contacts of 272.9 pm. The results of magnetic susceptibility measurements in the range of temperatures from 1.8 to 293 K and the 57Fe‐Mössbauer spectra in the range of temperatures from 2 to 300 K are reported. Compound 1 reacts with the lithiated acetylenes LiC=C–CMe3 and LiC=C–SiMe3 in n‐hexane to form the iron‐organic derivatives [Fe(C=C–R)(NPEt3)]4 [R = CMe3 ( 2 a ), R = SiMe3 ( 2 b )] keeping the heterocubane structure. Compounds 2 a and 2 b form crystals which are very reactive and also black. According to the crystal structure analysis 2 b has a Fe4N4 heterocubane structure which is less distorted than that in 1 with bond angles Fe–N–Fe of 85.5? and N–Fe–N of 94.2?. This leads to the longer Fe…Fe contacts of 281.4 pm. With the dimethylamido derivative Me3SiNP(NMe2)3 iron dichloride reacts under conditions similar to those in the synthesis of 1 to form the dark green mixed‐valenced FeII/FeIII cluster [Fe3Cl4{NP(NMe2)3}3] ( 3 ). According to the crystal structure analysis the three iron atoms in 3 are connected via one μ3‐N atom of a NP(NMe2)3– ligand, via two μ‐N atoms of the two remaining phosphoraneiminato ligands, and via one μ‐Cl atom to form an incomplete heterocubane skeleton. 相似文献
113.
Ulrike Riese Naim Faza Werner Massa Klaus Harms Thees Breyhan Paul Knochel Jürgen Ensling Vadim Ksenofontov Philipp Gütlich Kurt Dehnicke 《无机化学与普通化学杂志》1999,625(9):1494-1499
The phosphoraneiminato complexes [MnBr(NPEt3)]4 ( 1 ) and [M4Br5{NP(NMe2)3}3] with M = Mn ( 2 ) and M = Co ( 3 ) are prepared by melting reactions from the anhydrous metal dibromides with the silylated phosphaneimines Me3SiNPR3 (R = Et, NMe2) in the presence of potassium fluoride. All complexes are characterized by crystal structure analyses. 1 forms an only slightly distorted Mn4N4 heterocubane skeleton with an approximate Td symmetry and short Mn…Mn distances of average 295.7 pm. In the structures of 2 and 3 one μ3-NPEt3 ligand of 1 is replaced by one bromine atom with μ3-function. This leads to the novel heterocubane type M4N3Br with approximate C3 symmetry. The deformation of the cubic skeleton leads to metal-metal distances of different lengths, i. e. 292.7 and 323.6 pm in 2 and 274.4 and 306.2 pm in 3 . Temperature dependent magnetic susceptibility measurements between 300 and 5 K on 1 have shown that strong antiferromagnetic coupling exists between the Mn(II) ions with S = 5/2, with a large negative Weiss constant of Θ = –694 K. 相似文献
114.
Dr. Julienne K. Muenzner Dr. Bernhard Biersack Alexander Albrecht Tobias Rehm Dr. Ulrike Lacher Dr. Wolfgang Milius Prof. Dr. Angela Casini Dr. Jing‐Jing Zhang Prof. Dr. Ingo Ott Prof. Dr. Viktor Brabec Olga Stuchlikova Dr. Ion C. Andronache Leonard Kaps Prof. Dr. Dr. Detlef Schuppan Prof. Dr. Rainer Schobert 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(52):18953-18962
Four gold(I) carbene complexes featuring 4‐ferrocenyl‐substituted imidazol‐2‐ylidene ligands were investigated for antiproliferative and antivascular properties. They were active against a panel of seven cancer cell lines, including multidrug‐resistant ones, with low micromolar or nanomolar IC50 (72 h) values, according to their lipophilicity and cellular uptake. The delocalized lipophilic cationic complexes 8 and 10 acted by increasing the reactive oxygen species in two ways: through a genuine ferrocene effect and by inhibiting the thioredoxin reductase. Both complexes gave rise to a reorganization of the F‐actin cytoskeleton in endothelial and melanoma cells, associated with a G1 phase cell cycle arrest and a retarded cell migration. They proved antiangiogenic in tube formation assays with endothelial cells and vascular‐disruptive on real blood vessels in the chorioallantoic membrane of chicken eggs. Biscarbene complex 10 was also tolerated well by mice where it led to a volume reduction of xenograft tumors by up to 80 %. 相似文献
115.
Karl Grubmayr Ulrike Gabriella Wagner 《Monatshefte für Chemie / Chemical Monthly》1988,119(6-7):793-812
1H NMR-spectroscopic investigations of the acid catalyzed addition of methanol to dihydrodipyrrinones (Z)-2, (E)-2, and4 show the C-protonation of their enamide parts to be the first and rate determining step forming the key intermediate, the N-acyl-immonium ion N+. Its ability to add nucleophiles diastereoselectively can be used to prepare the adductsl-3 andl-5. Exclusive formation of thelike-isomer can be explained by a stereoelectronically favoured approach of the nucleophile and by the thermodynamically favoured arrangement of the bulky ring substituents. Both explanations are based on low temperature X-ray crystal structure determinations: in the first place, the orientation of the added nucleophile could be found to be nearly parallel to the -plane of the lactam unit and quasi-axial with respect to theenvelope-like conformation of the five-ring lactam; in the second place, the relative orientation of the methoxycarbonyl-metyl-group at C-3 and the pyrrolylmethyl-substituent at C-4 could be found to be atrans-quasi-diequatorial one. 相似文献
116.
Ulrike Kant Tobias Klauss Jürgen Voigt Matthias Weber 《Journal of Evolution Equations》2009,9(4):637-659
We treat the time evolution of states on a finite directed graph, with singular diffusion on the edges of the graph and glueing
conditions at the vertices. The operator driving the evolution is obtained by the method of quadratic forms on a suitable
Hilbert space. Using the Beurling–Deny criteria we describe glueing conditions leading to positive and to submarkovian semigroups,
respectively. 相似文献
117.
Nising CF Ohnemüller UK Friedrich A Lesch B Steiner J Schnöckel H Nieger M Bräse S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(13):3647-3654
Tetrahydroxanthenones, which can be easily prepared by a domino oxa-Michael aldol condensation, offer various possibilities for diastereoselective functionalization, giving access to the stereocontrolled synthesis of stereochemical triades or tetrades, which represent privileged structural motifs. In most cases, the relative stereochemistry was unequivocally established by crystal structure analysis. 相似文献
118.
Helge Hannebauer Thorsten Dullweber Ulrike Baumann Tom Falcon Rolf Brendel 《固体物理学:研究快报》2014,8(8):675-679
We evaluate industrial‐type PERC solar cells applying a 5 busbar front grid and fineline‐printed Ag fingers. We obtain finger widths down to 46 µm when using a stencil with 40 µm opening for the finger print, whereas the busbar is printed in a separate printing step with a different Ag paste (dual print). This compares to finger widths of 62 µm to 66 µm when applying print‐on‐print. The 5 busbar front grid with the best dual print process reduces the shadowing loss of the front grid to 4.0% compared to 5.8% for a conventional 3 busbar front grid printed with print‐on‐print. The 1.8% reduction in shadowing loss results in equal parts from the reduced finger width with dual print as well as from a reduced total busbar width of the 5 busbar design. The resulting PERC solar cells with 5 busbars demonstrate independently confirmed conversion efficiencies of 21.2% compared to 20.6% efficiency of the 3 busbar PERC solar cell. The increased conversion efficiency is primarily due to an increased short‐circuit current resulting from the reduced shadowing loss. To our knowledge, 21.2% conversion efficiency is the highest value reported so far for industry typical silicon solar cells with printed metal front and rear contacts. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
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