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1.
2.
Several salts containing the complex anions [CuCl
4]= or [CuBr
4]= have heen prepared, and their spectra have been measured and interpreted in terms of ligand-field theory. They exhibit a d-d band with
about 8–9000 cm–1, and several well defined charge-transfer bands in the visible and near ultraviolet spectral range. Several experimental facts, supported by theoretical considerations, indicate that the structure of the [CuX
4]= anions is not a truly tetrahedral, but a flattened tetrahedral one, of symmetry D
2d
. Details on the course of the endothermic solvolysis reactions which occur in polar organic solvents, and on the probable nature of the solvolysis products are reported and discussed.
Zusammenfassung Mehrere Salze der komplexen Anionen [CuCl 4]2– und [CuBr 4]2– wurden dargestellt, ihre Spektren gemessen und ligandenfeldtheoretisch interpretiert. Die Spektren zeigen eine d d-Bande mit im Gebiet von 8000 bis 9000 cm–1 und mehrere wohldefinierte Elektronenüberführungsbanden im sichtbaren und nahen ultravioletten Spektralbereich. Mehrere experimentelle Befunde, die von theoretischen Überlegungen unterstützt werden, deuten darauf hin, daß die [CuX 4]2/s--Anionen nicht rein tetraedrisch gebaut sind, sondern längs einer zweizähligen Achse gestauchte Tetraeder der Symmetrie D 2d darstellen.Einzelheiten über den Verlauf der endothermen Solvolysereaktionen in polaren organischen Lösungsmitteln und über die wahrscheinlichen Solvolyseprodukte werden mitgeteilt und diskutiert.
Résumé Plusieurs sels des anions complexes [CuCl 4]2– et [CuBr 4]2– ont été préparés et leurs spectres mesurés et interprétés dans le cadre de la théorie du champ des ligands.Ils montrent une bande d d avec dans la région de 8000 à 9000 cm–1 et plusieurs bandes bien définies du type «transfer de charges» dans le visible et l'ultraviolet proche. Plusieurs résultats expérimentaux, soutenus par des considérations théoriques, indiquent que la structure des ions [CuX 4]2– n'est pas celle d'un tétraèdre véritable mais celle d'un tétraèdre déformé, de symétrie D 2d , Des détails sur le cours des réactions endothermiques de solvolyse, qui ont lieu dans les solvants organiques polaires et sur la nature probable des produits de la solvolyse sont rapportés et discutés.相似文献
3.
We have performed a comparative study of the electronic properties of six different electron-doped metal-phthalocyanine (MPc) compounds (ZnPc, CuPc, NiPc, CoPc, FePc, and MnPc), in which the electron density is controlled by means of potassium intercalation. Despite the complexity of these systems, we find that the nature of the underlying molecular orbitals produces observable effects in the doping dependence of the electrical conductivity of the materials. For all the MPc's in which the added electrons are expected to occupy orbitals centered on the ligands (ZnPc, CuPc, and NiPc), the doping dependence of the conductivity has an essentially identical shape. This shape is different from that observed in MPc materials in which electrons are also added to orbitals centered on the metal atom (CoPc, FePc, and MnPc). The observed relation between the macroscopic electronic properties of the MPc compounds and the properties of the molecular orbitals of the constituent molecules clearly indicates the richness of the alkali-doped metal-phthalocyanines as a model class of compounds for the investigation of the electronic properties of molecular systems. 相似文献
4.
5.
H. B. Heersche P. Jarillo-Herrero J. B. Oostinga L. M.K. Vandersypen A. F. Morpurgo 《The European physical journal. Special topics》2007,148(1):27-37
The electronic transport properties of graphene exhibit
pronounced differences from those of conventional two dimensional
electron systems investigated in the past. As a consequence, well
established phenomena such as the integer quantum Hall effect and
weak localization manifest themselves differently in graphene. Here
we present an overview of recent experiments that we have performed
to probe phase coherent transport. In particular, we have
investigated in great detail Josephson supercurrent and
superconducting proximity effect in junctions consisting of a
graphene layer in between superconducting electrodes. We have also
used the same devices to measure aperiodic conductance fluctuations
and weak localization. The experimental results clearly indicate
that low-temperature transport in graphene is phase coherent on a
∼ 1μm length scale, irrespective of the position of the
Fermi level. We discuss the different behavior of Josephson
supercurrent and weak localization in terms of the unusual
properties of the electronic states in graphene upon time reversal
symmetry. 相似文献
6.
G. H. Boldingh Gay Astruc A. Jaworowsky Schacherl H. Mühe Richard Firbas Morpurgo A. Alder Jahoda G. Vulpius M. G. Denigès Maquenne Taine Bocquillon Soulard Barnouvin und F. Wichlog 《Fresenius' Journal of Analytical Chemistry》1902,41(3-4):260-268
Ohne Zusammenfassung 相似文献
7.
We report transport measurements through graphene on SrTiO(3) substrates as a function of magnetic field B, carrier density n, and temperature T. The large dielectric constant of SrTiO(3) very effectively screens long-range electron-electron interactions and potential fluctuations, making Dirac electrons in graphene virtually noninteracting. The absence of interactions results in an unexpected behavior of the longitudinal resistance in the N=0 Landau level and in a large suppression of the transport gap in nanoribbons. The "bulk" transport properties of graphene at B=0 T, on the contrary, are completely unaffected by the substrate dielectric constant. 相似文献
8.
9.
G. Morpurgo 《Fresenius' Journal of Analytical Chemistry》1902,41(2):123-124
Ohne Zusammenfassung 相似文献
10.
Mario Bossa Giorgio O. Morpurgo Laura Morpurgo 《Journal of Molecular Structure》1995,330(1-3):395-401
Semiempirical AM1 calculations were used to optimize the geometry of the adducts formed by 2,5-dihydroxy-p quinone (DHpQ) with substituted pyridines or imidazole. Hydrogen bond formation was seen to be responsible for the stability of the adducts. From the study of the total energy function, obtained by imposing fixed positions to the proton, two structures were found to be possible for each adduct, one schematically indicated as -OH … N-base and the proton transfer one, indicated as -O− … HN+base. The proton transfer energy was found to vary linearly with the base pKa value. A study was also carried out on the system formed by DHpQ and a cluster of three water molecules acting as proton acceptors. The implications were discussed relating to possible hydrogen bond formation between trihydroxyphenylalanine quinone, the coenzyme of bovine serum amine oxidase, and some basic residue or water molecule, lying close to the protein active site. 相似文献