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191.
192.
Martin Baumert Johannes Heinemann Ralf Thomann Rolf Mülhaupt 《Macromolecular rapid communications》2000,21(6):271-276
New families of highly branched polyethylenes containing alkyl short chain branches as well as polar and non‐polar long‐chain branches were prepared by combining migratory insertion copolymerization with controlled radical graft copolymerization. Key intermediate was a novel alkoxyamine‐functionalized 1‐alkene which was copolymerized with ethylene using a palladium catalyst. The resulting highly branched polyethylene with alkoxyamine‐functionalized short chain branches was used as macroinitiator to initiate controlled radical graft copolymerization of styrene and styrene/acrylonitrile. Novel polyethylene graft copolymers with molecular masses of Mw >100 000 g/mol and narrow polydispersities were obtained. Transmission electron microscopic studies (TEM) and the presence of two glass transition temperatures at –67 and +100°C indicated microphase separation. 相似文献
193.
194.
Axel Heinemann 《Nachrichten aus der Chemie》2004,52(11):1159-1161
195.
Chemistry of Polyfunctional Molecules. 128 [1]. Synthesis and Crystal Structure of N,N,N′,N″,N″-Pentamethyl-diethylene-triamine Cocoordinated Sodium Bis(diphenylphosphanyl)amide and about a [12]-Crown-4-Ether Derivative The metalation of bis(diphenylphosphanyl)amine [HN(PPh2)2 ( 4 )] with NaH in the presence of N,N,N′,N″,N″-pentamethyl-diethylene-triamine [PMDTA ( 2 )] at 105 °C in toluene affords the monomeric yellow sodium complex [(Ph2P)2NNa · PMDTA] ( 5 ). X-ray analysis reveals that the coordination sphere of the sodium ion consists of the chelating triamine ligand 2 and [N(PPh2)2]– as N- and monodentate P-donor. Additional weak η1 C-contacts to 2 and [N(PPh2)2]– are discussed. In the presence of [12]-crown-4-ether, HN(PPh2)2 and NaH react to the dimeric yellow-green complex [{(Ph2P)2NNa}2{[12]-crown-4}5] ( 6 ). The compound 6 crystallizes in thin needles, but they are not suitable for X-ray analysis. The dimeric non ionic structure of 6 has been confirmed by mass spectroscopy and conductivity measurements. 相似文献
196.
Cleavage reactions of the dinuclear [{Ni(′S2C ′)}2] · DMF (′S2C ′ 2– = 1,3‐imidazolidinyl‐N,N′‐bis(2‐benzenethiolate)(2–)) with HNPiPr3 or HNSPh2 yielded the mononuclear complexes [Ni(NHPiPr3)(′S2C ′)] ( 1 ) and [Ni(NHSPh2)(′S2C ′)] ( 2 ) which have been completely characterized. The nickel‐carbene‐dithiolate [Ni(′S2C ′)] moiety is one of the very rare complex fragments that are able to coordinate both HNPR3 or HNSR2. IR spectra and X‐ray structure determinations show that 1 and 2 exhibit intramolecular N–H…S(thiolate) hydrogen bonds. Geometric parameters and NMR spectroscopic data of 1 and 2 are compatible with N–X single bonds and ylidic structures of the HNPiPr3 and HNSPh2 ligands. Comparison of Ni–N distances in diamagnetic and paramagnetic [Ni(NHSPh2)] complexes was rendered possible through the X‐ray structure determination of the homoleptic [Ni(NHSPh2)6]Cl2 ( 3 ) which formed as minor by‐product in the synthesis of 2 . 相似文献
197.
198.
Rademacher P Heinemann C Jänsch S Kowski K Weiss ME 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2000,56(6):1179-1190
The UV photoelectron spectra of several tetracyclic heteroaromatic compounds (2-9) which are pi-isoelectronic with triphenylene (1) have been recorded and analysed making use of semiempirical AM1 and PM3 as well as ab initio/DFT B3LYP calculations. In one series of compounds (2-7), the peripheral benzene rings of 1 are successively substituted by thiophene rings that are either [b]- or [c]-annellated with the central benzene unit. In 2-7 only marginal shifts are found for most of the IPs of electrons. In the benzotrithiophenes 5-7, a systematic variation is displayed by IP(pi7). Compared to 1, the pi electron system of benzo[c]trithiophene (7) is approximately two times as much destabilized as in the isomers 5 and 6 with [b]annellated thiophene rings. The IP[n(S)] values of the thiophene derivatives 2-7 indicate that these orbitals are clearly destabilized relative to thiophene. The same holds for the n(O) orbital of the furane derivative 9 in comparison with that of furane. In 9, only the higher pi MOs (pi7-pi9) are destabilized whereas the lower levels (pi1-pi4) are stabilized, and those in between (pi5-pi6) remain essentially unshifted. In the pyrrole derivative 8, all pi MOs are substantially destabilized by about 0.5-1.6 eV relative to 1. 相似文献
199.
Saalfrank RW Prakash R Maid H Hampel F Heinemann FW Trautwein AX Böttger LH 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(9):2428-2433
Heptanuclear metal-centered, six-membered, mixed-valent, heterometallic wheels 1-3 of iron, manganese, and indium were prepared in a one-pot reaction from N-benzyldiethanolamine (H2L(1)), cesium carbonate, [PPh4]2[MnCl4], and FeCl3 or InCl3. All three complexes were characterized by the combination of elemental analysis, FAB mass spectroscopy, X-ray diffraction and cyclic voltammetry and in the case of 1 additionally by M?ssbauer spectroscopy. In 1, four Mn(II) ions in the periphery are arranged in pairs alternating with one Fe(III) ion each, with an Fe(III) ion located in the center. In 2, three Mn(II) ions alternate with three In(III) ions, whereas in 3, four In(III) ions are arranged in pairs and alternate with one Mn(II) ion each. In 2 and 3 an Mn(II) ion is encapsulated in the center. 相似文献
200.
Activation of SO2 and CO2 by Trivalent Uranium Leading to Sulfite/Dithionite and Carbonate/Oxalate Complexes
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Anna‐Corina Schmidt Frank W. Heinemann Dr. Christos E. Kefalidis Prof. Dr. Laurent Maron Dr. Peter W. Roesky Prof. Dr. Karsten Meyer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(42):13501-13506
The first sulfite [{((nP,MeArO)3tacn)UIV}2(μ‐κ1:κ2‐SO3)] (tacn=triazacyclononane) and dithionite [{((nP,MeArO)3tacn)UIV}2(μ‐κ2:κ2‐S2O4)] complexes of uranium from reaction with gaseous SO2 have been prepared. Additionally, the reductive activation of CO2 was investigated with respect to the rare oxalate [{((nP,MeArO)3tacn)UIV}2(μ‐κ2:κ2‐C2O4)] formation. This ultimately provides the unique S2O42?/C2O42? and SO32?/CO32? complex pairs. All new complexes were characterized by a combination of single‐crystal X‐ray diffraction, elemental analysis, UV/Vis/NIR electronic absorption, IR vibrational, and 1H NMR spectroscopy, as well as magnetization (VT SQUID) studies. Moreover, density functional theory (DFT) calculations were carried out to gain further insight into the reaction mechanisms. All observations, together with DFT, support the assumption that SO2 and CO2 show similar (dithionite/oxalate) to analogous (sulfite/carbonate) activation behavior with uranium complexes. 相似文献