physicochemical properties in the crystalline bulk and in thin films deposited from the gas phase

Four analogues of the spin-crossover complex [Fe(H2Bpz2)2(phen)] (H2Bpz2 = dihydrobis(pyrazolyl)borate; 2) containing functionalized 1,10-phenanthroline (phen) ligands have been prepared; i.e., [Fe(H2Bpz2)2(L)], L = 4-methyl-1,10-phenanthroline (3), 5-chloro-1,10-phenanthroline (4), 4,7-dichloro-1,10-phenanthroline (5), and 4,7-dimethyl-1,10-phenanthroline (6). The systems are investigated by magnetic susceptibility measurements and a range of spectroscopies in the solid state and in thin films obtained by physical vapour deposition (PVD). Thermal as well as light-induced SCO behaviour is observed for 3–6 in the films. By contrast, thermal SCO in the solid state occurs only for 3 and 4 but is absent for 5 and 6. These findings are discussed in the light of cooperative and intermolecular interactions

[1,2-Bis(diphenyl­phosphino)ethane]{2-[bis­(diphenyl­phosphinometh­yl)amino]pyridinium}fluoridohydrazidato­molybdenum(IV) bis­(tetra­fluoridoborate)

In the crystal structure of the title compound, [MoF(N2H2)(C31H29N2P2)(C26H24P2)](BF4)2, each Mo atom is surrounded by four P atoms of one 1,2-bis­(diphenyl­phosphino)ethane and one 2-[bis­(diphenyl­phosphinometh­yl)amino]pyridinium ligand. The remaining binding sites of the distorted octa­hedron are occupied by a hydrazidate (NNH2 2−) and a fluoride ligand. Two F atoms of an anion are disordered over two positions; the site occupancy factors are ca 0.7 and 0.3

N2 Reduction versus H2 Evolution in a Molybdenum- or Tungsten-Based Small-Molecule Model System of Nitrogenase

Molybdenum dinitrogen complexes have played a major role as catalytic model systems of nitrogenase. In comparison, analogous tungsten complexes have in most cases found to be catalytically inactive. Herein, a tungsten complex was shown to be supported by a pentadentate tetrapodal (pentaPod) phosphine ligand, under conditions of N2 fixation, primarily catalyzes the hydrogen evolution reaction (HER), in contrast to its Mo analogue, which catalytically mediates the nitrogen-reduction reaction (N2 RR). DFT calculations were employed to evaluate possible mechanisms and identify the most likely pathways of N2 RR and HER activities exhibited by Mo- and W-pentaPod complexes. Two mechanisms for N2 RR by PCET are considered, starting from neutral (M(0) cycle) and cationic (M(I) cycle) dinitrogen complexes (M=Mo, W). The latter was found to be energetically more favorable. For HER three scenarios are treated; that is, through bimolecular reactions of early M-Nx Hy intermediates, pure hydride intermediates or mixed M(H)(Nx Hy ) species

Visualizing Intersecting Sets: Information Systems Applications in Academia and Business

Data visualization plays a crucial role in enhancing the communication capabilities of information systems through high-quality visual diagrams. Traditional techniques for depicting set intersections, i.e., Euler and Venn diagrams, offer limited information density and scalability. This paper examines an alternative approach, UpSet, which provides richer informational output and has gained acceptance across various disciplines. Despite its wide adoption, the Information Systems (IS) community has not yet fully recognized UpSet\u27s potential. We introduce UpSet to the IS audience, demonstrating its utility through academic and business examples relevant to IS. Additionally, we discuss its general applicability in research, highlighting how UpSet can significantly improve set-intersecting visualization

Experimental Investigations of the Multiple Impulse Energy Handling Capability of Metal-Oxide Varistors for Applications in Electrical Power Engineering Translation of: Experimentelle Untersuchungen zur Mehrfachimpulsbelastbarkeit von Metalloxidvaristoren für Anwendungen in der elektrischen Energietechnik

In this thesis, the results of the research on multiple impulse energy handling capability of metal-oxide varistors (MOVs) are described. The focus here is on repetitive impulse stresses with a high energy density where the specimens cool down to ambient temperature after each energy injection. The repetitive energy injection handling capability of MOVs is compared to their single impulse energy handling capability. It is widely known that the single impulse energy handling capability of MOVs increases with the current density of the impulse stress. This is due to the homogeneous current distribution within MOVs when applying higher current densities. The findings described in this thesis suggest that the temperature dependence of electrical resistance causes a further homogenization of the current distribution within the material of the MOVs at higher current densities. However, the impact of this seems to be small as its influence on the single impulse energy handling capability of the MOVs is not measurable. Furthermore, the results of experiments conducted for this thesis show that short interruptions of longduration current impulse stresses up to the range of seconds do not increase the impulse energy handling capability of MOVs. Additionally, the research results illustrate that the repetitive impulse energy handling capability of MOVs does not correlate with their single impulse energy handling capability. Concerning repetitive energy injections at lower current densities, the stress handling capability is very close to the single impulse energy handling capability. However, repetitive impulse stresses with higher current densities cause a reduced stress handling capability compared to the single impulse energy handling capability. Nonetheless, the energy handling capability when applying repetitive energy injections does not drop below the characteristic volume-related nominal energy handling capability of standard surge arresters. With regard to these findings, it is also shown that a change in reference voltage due to prior repetitive stressing of the MOV is not a sure sign for a pre-damage that leads to a decrease in single impulse energy handling capability. The results gained from this research are discussed with regard to routine tests of MOVs, the usage of surge arresters within electric power systems and the international standardization of surge arresters

[Bis(diphenyl­phosphino)methane-κ2 P,P′][bis­(diphenyl­phosphinometh­yl)diethoxy­silane-κ2 P,P′]bis­(dinitro­gen)­molybdenum(0) benzene 0.7-solvate

In the crystal structure of the title compound, [Mo(C25H22P2)(C30H34O2P2Si)(N2)2]·0.7C6H6, the Mo atoms are coordinated by four P atoms and two N atoms in a distorted octa­hedral mode. The two C atoms of one of the two eth­oxy groups are disordered and were refined using a split model and site-occupation factors of 0.7:0.3. The crystal structure contains a benzene solvent mol­ecule with a site occupation of 70%

Spin-Crossover Molecules on Surfaces: From Isolated Molecules to Ultrathin Films

Molecular spintronics seeks to use single or few molecules as functional building blocks for spintronic applications, directly relying on molecular properties or properties of interfaces between molecules and inorganic electrodes. Spin-crossover molecules (SCMs) are one of the most promising classes of candidates for molecular spintronics due to their bistability deriving from the existence of two spin states that can be reversibly switched by temperature, light, electric fields, etc. Building devices based on single or few molecules would entail connecting the molecule(s) with solid surfaces and understanding the fundamental behavior of the resulting assemblies. Herein, the investigations of SCMs on solid surfaces, ranging from isolated single molecules (submonolayers) to ultrathin films (mainly in the sub-10 nm range) are summarized. The achievements, challenges and prospects in this field are highlighted

Zur Ergotismusepidemie im Regierungsbezirk Breslau

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Copper-Catalyzed Monooxygenation of Phenols: Evidence for a Mononuclear Reaction Mechanism

The CuI salts [Cu(CH3 CN)4 ]PF and [Cu(oDFB)2 ]PF with the very weakly coordinating anion Al(OC(CF3 )3 )4- (PF) as well as [Cu(NEt3 )2 ]PF comprising the unique, linear bis-triethylamine complex [Cu(NEt3 )2 ]+ were synthesized and examined as catalysts for the conversion of monophenols to o-quinones. The activities of these CuI salts towards monooxygenation of 2,4-di-tert-butylphenol (DTBP-H) were compared to those of [Cu(CH3 CN)4 ]X salts with "classic" anions (BF4- , OTf- , PF6- ), revealing an anion effect on the activity of the catalyst and a ligand effect on the reaction rate. The reaction is drastically accelerated by employing CuII -semiquinone complexes as catalysts, indicating that formation of a CuII complex precedes the actual catalytic cycle. This result and other experimental observations show that with these systems the oxygenation of monophenols does not follow a dinuclear, but a mononuclear pathway analogous to that of topaquinone cofactor biosynthesis in amine oxidase

Kupfer‐katalysierte Monooxygenierung von Phenolen: Evidenz für einen mononuklearen Reaktionsmechanismus

Die CuI-Salze [Cu(CH3CN)4]PF und [Cu(oDFB)2]PF mit dem sehr schwach koordinierenden Anion Al(OC(CF3)3)4− (PF), sowie [Cu(NEt3)2]PF mit dem einzigartigen, linearen Bis-Triethylamin-Komplex [Cu(NEt3)2]+ wurden synthetisiert und als Katalysatoren für die Umwandlung von Monophenolen zu o-Chinonen untersucht. Die Aktivitäten dieser CuI-Salze bei der Monooxygenierung von 2,4-Di-tert-butylphenol (DTBP-H) wurden mit denen der [Cu(CH3CN)4]X-Salze mit “klassischen” Anionen (BF4−, OTf−, PF6−) verglichen, wobei ein Anioneneffekt auf die Aktivität des Katalysators und ein Ligandeneffekt auf die Reaktionsgeschwindigkeit festgestellt wurden. Letztere wird durch den Einsatz von CuII-Semichinon-Komplexen als Katalysatoren drastisch erhöht, was darauf hinweist, dass die Bildung eines CuII-Komplexes dem eigentlichen katalytischen Zyklus vorausgeht. Diese und andere experimentelle Erkenntnisse zeigen, dass die Oxygenierung von Monophenolen mit den oben genannten Systemen nicht einem dinuklearen, sondern einem mononuklearen Weg folgt, analog zur Topachinon-Cofaktor-Biosynthese im Enzym Aminoxidase