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991.
Teles Wagner M. Fernandes Nelson G. Abras Anuar Filgueiras Carlos A. L. 《Transition Metal Chemistry》1999,24(3):321-325
The coordinating ability of the ligand di(2-pyridyl)sulphide, dps, was studied in several situations. Dps behaved as a bidentate chelating agent with SnX4 (X=Cl or Br) and also with Pd and Pt (PdCl2 and K2PtCl4), whereas with [Pt2(PR3)2Cl4], (R = Et or Ph), it formed bridging complexes: [{Pt(PR3)Cl2}2-dps]. The crystal and molecular structure of [{Pt(PEt3)Cl2}2-dps] was determined. This complex, as well as [M(dps)Cl2], (M = Pd or Pt), underwent reactions with SnCl2, which inserts into the M–Cl bonds producing heterobimetallic products, which are important in catalysis. 相似文献
992.
N(B(NMe2)2)(Si(NMe2)3) (Ti(NMe2)3), [N(Si(NMe2)3)(Ti(NMe2)2)]2 und N(SiMe3)(Si(NMe2)3)(Ti(NMe2)3) — Synthesis and Characterization of New Molecular Single-source Precursors for Nitride and Carbonitride Ceramics Synthesis and spectroscopic data of the title compounds are reported. [N(Si(NMe2)3)(Ti(NMe2)2)]2 crystallizes in the space group P1 , a = 8.406(7), b = 10.673(8), c = 10.872(6) Å, α = 68.45(4)°, β = 71.72(4)°, γ = 78.11(7)°, 2 877 diffractometer data (Fo ? 2σFo), R = 0.051. The compound is characterized by a planar four-membered Ti2N2-ring with exocyclic tris(dimethylamino)silyl substituents attached to the nitrogen atoms of the ring. 相似文献
993.
The model system Pd/TiO2 (110) was used to evaluate the correlation between metal encapsulation and electronic structure of TiO2 crystals. We observed encapsulation of Pd clusters supported on TiO2 crystals, which were heavily Ar+ sputtered, Nb-doped, or reduced by vacuum annealing. In contrast, encapsulation was not observed on unreduced, undoped, or slightly sputtered TiO2 crystals. Our results indicate a strong dependence of the encapsulation process on the electron density in the conduction band of TiO2 and on the space charge formed at Pd/TiO2 interfaces. This behavior is controlled by the initial position of the Fermi energy level (EF) of the metal and the oxide before contact is established. We proved that encapsulation reactions are favored by n-type doping of the oxide and a large work function of the metal. On the basis of this mechanism, we conclude on general trends controlling encapsulation reactions of oxide-supported metal clusters and the strong metal-support interaction (SMSI). 相似文献
994.
Joyce Y. Corey Elizabeth A. Francis Marian S. Bursten Joan C. Kunz 《Journal of organometallic chemistry》1981,210(2):149-161
Ring enlargement of silicon heterocycles is accomplished from derivatives which contain an exocyclic chloromethyl substituent by reaction with aluminum halide catalyst or with potassium fluoride. Tricyclic derivatives with a silicon atom in a central five-, six-, or seven-membered ring form silins, silepins and silocins, respectively, and are isolated by quenching the product chlorosilanes with H2O, MeOH, Na/MeOH, LiAlH4, MeMgBr or MeLi. A stoichiometric quantity of fluoride ion also results in conversion of 9-chloromethyl-9-silaanthracene to 5-fluoro-dibenzo[b,e] silepin but the percent conversion of the 9-iodomethyl precursor is higher. The limitations of the two methods are discussed briefly. 相似文献
995.
Ohne Zusammenfassung 相似文献
996.
997.
998.
Steinmetz K Noterdaeme J Wagner F Wesner F Bäumler J Becker G Bosch HS Brambilla M Braun F Brocken H Eberhagen A Fritsch R Fussmann G Gehre O Gernhardt J v Gierke G Glock E Gruber O Haas G Hofmann J Hofmeister F Izvozchikov A Janeschitz G Karger F Keilhacker M Klüber O Kornherr M Lackner K Lisitano G van Mark E Mast F Mayer HM McCormick K Meisel D Mertens V Müller ER Murmann H Niedermeyer H Poschenrieder W Puri S Rapp H Röhr H Ryter F Schmitter K Schneider F Setzensack C Siller G Smeulders P 《Physical review letters》1987,58(2):124-127
999.
1000.
Gray microcrystalline powders of ScTaN(2) were prepared from solid-state reactions of delta-ScN with Ta(3)N(5) powders at T = 1770 K. According to thermal analyses the compound is stable against oxidation by O(2) up to temperatures of T = 800 K. In an Ar atmosphere ScTaN(2) decomposes above T = 1250 K and in a N(2) atmosphere above T = 2000 K under release of N(2) to form delta-ScN and beta-Ta(2)N. The crystal structure (space group P6(3)/mmc, No. 194, a = 305.34(3) pm, c = 1056.85(9) pm, Z = 2) was refined on the basis of X-ray and neutron powder diffraction data. It comprises alternating layers of ScN(6/3) octahedra and trigonal TaN(6/3) prisms, which are also observed in the binary nitrides delta-ScN and theta-TaN, respectively. A small degree of anti-site defects (about 5%) was detected. Only a small solubility of ScN in epsilon-TaN was observed, while the solubility of TaN in delta-ScN is >/=10 mol % at T = 1820 K. ScTaN(2) is a diamagnetic small gap semiconductor or a semimetal, as inferred from magnetization and electrical resistivity measurements, consistent with band structure calculations. Chemical bonding analyses with the COHP method yield significant covalent Ta-Ta interactions. Topological analyses of the electron localization function reveal unexpected Ta-Ta three-center bonding basins within seemingly empty trigonal prisms of the TaN(6/3) layers. 相似文献