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181.
Dipl.‐Chem. Fabian Schax Dr. Eckhard Bill Dr. Christian Herwig Prof. Dr. Christian Limberg 《Angewandte Chemie (International ed. in English)》2014,53(47):12741-12745
The reaction of a tripodal trisilanol with n‐butyllithium and CrCl2 results in a dinuclear CrII complex ( 1 ), which is capable of cleaving O2 to yield in a unique complex ( 2 ) with an asymmetric diamond core composed of two CrIV?O units. Magnetic susceptibility data reveal significant exchange coupling of CrII (S=2) in 1 and large zero‐field splitting for CrIV (S=1) in 2 owing to strong spin–orbit coupling of the ground state. The CrIV?O compound can also be generated using PhIO, and evidence was gathered that although it is the stable product isolated after excessive O2 treatment, it further activates O2 to yield an intermediate species that oxidizes THF or Me‐THF. By extensive 18O labeling studies we were able to show, that in the course of this process 18O2 exchanges its label with siloxide O atoms of the ligand via terminal oxido ligands. 相似文献
182.
Origin and Location of Electrons and Protons during the Formation of Intermetalloid Clusters [Sm@Ga3−xH3−2xBi10+x]3− (x=0, 1)
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Dipl.‐Chem. Bastian Weinert B.Sc. Fabian Müller Dr. Klaus Harms Dr. Rodolphe Clérac Prof. Dr. Stefanie Dehnen 《Angewandte Chemie (International ed. in English)》2014,53(44):11979-11983
Reaction of [GaBi3]2? with [Sm(C5Me4H)3] yielded the first protonated ternary intermetalloid clusters [Sm@Ga3?xH3?2xBi10+x]3? ( 1 ; x=0,1). The presence of the Ga? H bonds and the transfer of electrons and protons during the formation of 1 were elucidated by a combination of experimental and quantum chemical methods, thereby rationalizing the role of the solvent ethane‐1,2‐diamine as a Brønsted acid. As an organic by‐product, we observed the previously unknown octamethylfulvene ( 2 ) upon C? C coupling of (C5Me4H)?. 相似文献
183.
184.
Janina A. Werra Marius A. Wünsche Patrick Rathmann Paul Mehlmann Pawel Löwe Fabian Dielmann 《无机化学与普通化学杂志》2020,646(13):794-799
Phosphoniumylidyl and phosphazenyl groups are effective substituents to increase the electron-donating ability of tertiary phosphines. However, the influence of structural variations among those substituents on the electronic properties of the phosphines is little explored. Herein, we show that protonation of the ylidic carbon atom of phosphoniumylidyl phosphines increases the Tolman electronic parameter (TEP) by ΔTEP = 16.0–18.8 cm–1. Furthermore, phosphazenyl phosphines were synthesized with isopropyl groups (NP{iPr}3) and tetramethylguanidino groups (NP{tmg}3) at the phosphonium center. Determination of their TEP values reveals a remarkable low substituent parameter of χ = –18.5 cm–1 for the NP(tmg)3 group. In addition, we prepared the corresponding gold(I) complexes and determined their solid-state structures using single-crystal X-ray diffraction studies to analyze the steric profile of the new phosphine ligands. 相似文献
185.
Fabian Dankert H. Lars Deubner Matthias Müller Magnus R. Buchner Florian Kraus Carsten von Hänisch 《无机化学与普通化学杂志》2020,646(18):1501-1507
The work describes unexpected stoichiometric C–F bond cleavage reactions of beryllium, magnesium, gallium, hafnium and thorium halides with α,α,α-trifluorotoluene. The reaction of BeBr2 / GaBr3 or MgBr2 / GaBr3 mixtures as well as neat GaI3 with α,α,α-trifluorotoluene in the presence of (OSi2Me4)2 ( I ) yields the carbenium ion containing compounds [Ph-C(O2Si2Me4)][GaX4] (X = Br: 1 , X = I/F: 2 ). Both compounds were successfully characterized and a defluorination type reaction under incorporation of a siloxy unit was observed. Compound 1 was also characterized by single-crystal X-ray diffraction analysis. The conversion of α,α,α-trifluorotoluene with BeI2, HfI4 or ThI4 turned out to be a halodefluorination-type reaction with formation of α,α,α-triiodotoluene ( 3 ). An adequate NMR spectroscopic and the X-ray crystallographic characterization of 3 were performed for the first time. 相似文献
186.
Philipp Rotering Lukas F. B. Wilm Janina A. Werra Dr. Fabian Dielmann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(2):406-411
Electron-rich tertiary phosphines are valuable species in chemical synthesis. However, their broad application as ligands in catalysis and reagents in stoichiometric reactions is often limited by their costly synthesis. Herein, we report the synthesis and properties of a series of phosphines with 1-alkylpyridin-4-ylidenamino and 1-alkylpyridin-2-ylidenamino substituents that are accessible in a very short and scalable route starting from commercially available aminopyridines and chlorophosphines. The determination of the Tolman electronic parameter (TEP) value reveals that the electron donor ability can be tuned by the substituent pattern at the aminopyridine backbone and it can exceed that of common alkylphosphines and N-heterocyclic carbenes. The potential of the new phosphines as strong nucleophiles in phosphine-mediated transformations is demonstrated by the formation of Lewis base adducts with CO2 and CS2. In addition, the coordination chemistry of the new phosphines towards CuI, AuI, and PdII metal centers has been explored, and a convenient procedure to introduce the most basic phosphine into metal complexes starting from air-stable phosphonium salt is described. 相似文献
187.
Martin Piesch Dr. Fabian Dielmann Stephan Reichl Prof. Dr. Manfred Scheer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(7):1518-1524
A systematic study on the reactivity of the triple-decker complex [(Cp’’’Co)2(μ,η4:η4-C7H8)] ( A ) (Cp’’’=1,2,4-tritertbutyl-cyclopentadienyl) towards sandwich complexes containing cyclo-P3, cyclo-P4, and cyclo-P5 ligands under mild conditions is presented. The heterobimetallic triple-decker sandwich complexes [(Cp*Fe)(Cp’’’Co)(μ,η5:η4-P5)] ( 1 ) and [(Cp’’’Co)(Cp’’’Ni)(μ,η3:η3-P3)] ( 3 ) (Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) were synthesized and fully characterized. In solution, these complexes exhibit a unique fluxional behavior, which was investigated by variable temperature NMR spectroscopy. The dynamic processes can be blocked by coordination to {W(CO)5} fragments, leading to the complexes [(Cp*Fe)(Cp’’’Co)(μ3,η5:η4:η1-P5){W(CO)5}] ( 2 a ), [(Cp*Fe)(Cp’’’Co)(μ4,η5:η4:η1:η1-P5){(W(CO)5)2}] ( 2 b ), and [(Cp’’’Co)(Cp’’’Ni)(μ3,η3:η2:η1-P3){W(CO)5}] ( 4 ), respectively. The thermolysis of 3 leads to the tetrahedrane complex [(Cp’’’Ni)2(μ,η2:η2-P2)] ( 5 ). All compounds were fully characterized using single-crystal X-ray structure analysis, NMR spectroscopy, mass spectrometry, and elemental analysis. 相似文献
188.
Leiming Zhu Leonard Himmel Jean Michél Merkes Prof. Dr. Fabian Kiessling Prof. Dr. Magnus Rueping Dr. Srinivas Banala 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(19):4232-4235
Atropisomerism has been observed in a variety of biaryl compounds and meso-aryl substituted porphyrins. However, in porphyrins, this phenomenon had been shown only with o-substituted 6-membered aromatic groups at the meso-position. We show herein that a 5-membered heteroaromatic (N-mesyl-pyrrol-2-yl) group at the meso-position leads to atropisomerism. In addition, we report a ‘one-pot’ synthetic route for the synthesis of ‘all-pyrrolic’ porphyrin (APP) with several N-protection groups (Boc, Cbz, Ms and Ts). Among these groups, we found that only the Ms group gave four individually separable atropisomers of meso-tetra(N-Ms-pyrrol-2-yl) porphyrin. Furthermore, the reductive removal of Cbz- was achieved to obtain meso-tetra(pyrrol-2-yl) porphyrin. Thus, our synthetic procedure provides an easy access to a group of APPs and stable atropisomers, which is expected to expand the application of novel APP-based materials. 相似文献
189.
Alexander V. Fejzagić Sebastian Myllek Fabian Hogenkamp Julian Greb Prof. Dr. Jörg Pietruszka Dr. Thomas Classen 《ChemistryOpen》2020,9(9):959-966
Screening for an interesting biocatalyst and its subsequent kinetic characterization depends on a reliable activity assay. In this work, a fluorometric assay based on the halogenation of 4-methyl-7-diethylamino-coumarin was established to monitor haloperoxidase-activity. Since haloperoxidases utilize hydrogen peroxide and halide ions to halogenate a broad range of substrates by releasing hypohalous acids, a direct quantification of haloperoxidase-activity remains difficult. With the system presented here, 3-bromo-4-methyl-7-diethylaminocoumarin is preferentially formed and monitored by fluorescence measurements. As starting material and product share similar spectroscopical properties, a two-dimensional calibration ap-proach was utilized to allow for quantification of each compound within a single measurement. To validate the system, the two-dimensional Michaelis-Menten kinetics of a vanadium-dependent chloroperoxidase from Curvularia inaequalis were recorded, yielding the first overall kinetic parameters for this enzyme. With limits of detection and quantification in the low μm range, this assay may provide a reliable alternative system for the quantification of haloperoxidase-activity. 相似文献
190.