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101.
The inorganic-organic coordination polymer infin; 2[Cu2I2(μ-4-4′-bipyridine)] was prepared by the reaction of Cu(I)I and 4,4′-bipyridine in acetonitrile. Its structure consists of staircase-like CuX double chains which are connected to sheets by the 4,4′-bipyridine ligands. The thermal decomposition of the corresponding 1:1 copper(I) halide-4,4′-bipyridine compounds infin; 2[CuX(μ-4-4′-bipyridine)] (X = Cl, Br, I) was investigated using simultaneous difference thermal analysis and thermogravimetry (DTA-TG), thermomicroscopy, and temperature resolved X-ray powder diffraction in air or argon. Upon heating infin; 2[CuX(μ-4-4′-bipyridine)], several changes in sample mass are observed which correspond to a stepwise loss of the organic ligands. Temperature-resolved X-ray powder diffraction proves that infin; 2[CuX(μ-4-4′-bipyridine)] transforms to infin; 2[Cu2 X 2(μ-4-4′-bipyridine)] during the decomposition; the latter looses the remaining ligands when heated further, forming the corresponding copper(I)halides. When the experiments were performed under an argon atmosphere, the 2:1 coordination polymers were obtained as phase-pure compounds. 相似文献
102.
Dr. Matthew M. D. Roy Samuel R. Baird Dr. Eike Dornsiepen Lucas A. Paul Linkun Miao Dr. Michael J. Ferguson Dr. Yuqiao Zhou Prof. Dr. Inke Siewert Prof. Dr. Eric Rivard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(33):8572-8579
The synthesis of the new bulky vinyllithium reagent (MeIPr=CH)Li, (MeIPr=[(MeCNDipp)2C]; Dipp=2,6-iPr2C6H3) is reported. This vinyllithium precursor was found to act as a general source of the anionic 2σ, 2π-electron donor ligand [MeIPr=CH]−. Furthermore, a high-yielding route to the degradation-resistant SiII precursor MeIPr⋅SiBr2 is presented. The efficacy of (MeIPr=CH)Li in synthesis was demonstrated by the generation of a complete inorganic divinyltetrelene series (MeIPrCH)2E: (E=Si to Pb). (MeIPrCH)2Si: represents the first two-coordinate acyclic silylene not bound by heteroatom donors, with dual electrophilic and nucleophilic character at the SiII center noted. Cyclic voltammetry shows this electron-rich silylene to be a potent reducing agent, rivalling the reducing power of the 19-electron complex cobaltocene (Cp2Co). 相似文献
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104.
The reaction of different metal salts with 4‐(3‐phenylpropyl)pyridine (ppp) lead to the formation of compounds of composition M(NCS)2(ppp)4 [M = Mn ( Mn‐1 ); Fe ( Fe‐1 ), Ni ( Ni‐1 ); Cd ( Cd‐1 )], M(NCS)2(ppp)2(H2O)2 [M = Mn ( Mn‐2 ); Ni ( Ni‐2 )] and [M(NCS)2(ppp)2]n [M = Mn ( Mn‐3 ); Ni ( Ni‐3 ); Cd ( Cd‐3 )]. On heating compounds M‐1 decompose without the formation of any ppp deficient intermediate. In contrast, on heating, Ni‐2 transforms into a compound of composition M(NCS)2(ppp)2 that does not correspond to Ni‐3 . Unfortunately, this compound is of low crystallinity and therefore, its structure cannot be determined. The crystal structures of compounds M‐1 and M‐2 consist of discrete complexes, in which the metal cations are octahedrally coordinated. In compounds M‐3 the metal cations are linked by pairs of μ‐1,3‐bridging anions into chains. IR spectroscopic investigations show, that the value of the asymmetric CN stretching vibration depend on the coordination mode of the anionic ligand as well as on the nature of the metal cation. Magnetic measurements reveal that Ni‐3 shows only Curie‐Weiss behavior without any magnetic anomaly. A similar behavior is also found for Ni‐3 . Comparison of the magnetic properties of Ni‐3 with those of similar compounds indicates that the magnetic properties are only minor influenced by the Co‐ligand. 相似文献
105.
Siewert I Limberg C Demeshko S Hoppe E 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(30):9377-9388
A ligand that offers two parallel malonate binding sites linked by a xanthene backbone, namely, Xanthmal2-, has been utilised to synthesise dinuclear FeII complex [Fe2(Xanthmal)2] (1). The reactivity of 1 in contact with O2 was investigated at -40 degrees C and room temperature. After activation of O2 through interaction with both iron centres the ligand is oxidised: at the Calpha position monooxygenation and peroxide formation occur, partially accompanied by C-C bond cleavage to yield alpha-keto ester groups. To reveal mechanistic details investigations concerning 1) peroxide decomposition, 2) the reactivity of a corresponding mononuclear complex, 3) the influence of monooxygenation of the ligand on the reactivity and 4) product formation in dependence on time were carried out. The results can be explained by postulating formation of high-valent Fe intermediates and ligand-to-metal electron transfer, and the mechanistic scheme derived includes several steps that mimic the (suggested) functioning of non-heme iron enzymes. In agreement with this proposal, ligand oxidation can also be performed catalytically. Furthermore, we show that via a competitive route [(Xanthmal)2Fe2O] (2) is formed, which is unreactive towards O2 and thus is a dead end with respect to ligand oxidation. Both compounds 1 and 2 were fully characterised, and their properties are discussed. 相似文献
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109.
Stausholm-Møller J Kristoffersen HH Hinnemann B Madsen GK Hammer B 《The Journal of chemical physics》2010,133(14):144708
We present a systematic study of electronic gap states in defected titania using our implementation of the Hubbard-U approximation in the grid-based projector-augmented wave density functional theory code, GPAW. The defects considered are Ti interstitials, O vacancies, and H dopants in the rutile phase of bulk titanium dioxide. We find that by applying a sufficiently large value for the Hubbard-U parameter of the Ti 3d states, the excess electrons localize spatially at the Ti sites and appear as states in the band gap. At U=2.5?eV, the position in energy of these gap states are in fair agreement with the experimental observations. In calculations with several excess electrons and U=2.5?eV, all of these end up in gap states that are spatially localized around specific Ti atoms, thus effectively creating one Ti(3+) ion per excess electron. An important result of this investigation is that regardless of which structural defect is the origin of the gap states, at U=2.5?eV, these states are found to have their mean energies within a few hundredths of an eV from 0.94 eV below the conduction band minimum. 相似文献
110.
Chen Y Palmer RE Wilcoxon JP 《Langmuir : the ACS journal of surfaces and colloids》2006,22(6):2851-2855
Time-lapse studies of a film of passivated gold nanoparticles under electron beam irradiation have been performed using a transmission electron microscope, revealing the microscopic dynamics of the sintering process at the single nanoparticle level. It is found that the sintering of individual passivated gold nanoparticles under electron irradiation is local and mainly depends on the sensitivity of the passivating ligands to the electron beam. A multilayer film is less stable than monolayer film, consistent with the enhanced generation of secondary electrons. The observations also reveal a significant difference between the sintering of passivated nanoparticles and bare metal particles, especially regarding the size effect on the sintering rate. The formation of a neck between adjacent nanoparticles further indicates a mechanism driven by surface diffusion rather than Ostwald ripening at the initial sintering stage. 相似文献