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91.
Raimund Schwarz Günter Gliemann Laurent Chassot Philippe Jolliet Alex von Zelewsky 《Helvetica chimica acta》1989,72(2):224-236
The polarized optical absorption and emission (spectra, decay times) of single crystals of [Pd(thpy)2] and [Pt(thpy)2] (thpy ≡ C(3′)-deprotonated form of 2-(2-thienyl)pyridine) at temperatures 1.9 K ? T ? 80 K are reported. The emission of [Pt(thpy)2] can be influenced strongly by applied magnetic fields (0 ? H ? 6 T). Depending on the central ions Pd and Pt, the lowest excited electronic states of the single complexes are ligand-centered (LC) states and metal-to-ligand charge transfer (MLCT) states, respectively. This difference leads to distinctly dissimilar properties of the emission of both compounds. The experimental data show that the emission of single crystals of [Pd(thpy)2] and [Pt(thpy)2] at T ? 30 K originates from several types of traps (defect states of symmetry 3B2?stabilized below the exciton band) with LC and MLCT character, respectively. In the Pt compound, the 3B2 is split by spin-orbit coupling into three states. The states B and A, which determine the emission properties, are separated by Δv ~ 13 cm?1. Both states can mix under the influence of an applied magnetic field yielding an increase of the emission intensity by a factor of ~ 1.5 at H = 6 T. 相似文献
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97.
Helmut Schwarz Wolfgang Mathar Ferdinand Bohlmann 《Journal of mass spectrometry : JMS》1974,9(1):84-87
The methyl cleavage from piperidides of type CH3(CH?CH)nCONC5H10 with n = 1 to 3 does not proceed via ring contraction as shown earlier with n = 0. The fragmentation can be formulated with the concept of neighbouring group participation of the amide function which leads to a cyclic transition state. Investigations with a 2H-labelled compound in the case of n = 1 as well as energy measurements (AP, IP, Ek) agree with this assumption. 相似文献
98.
Synthesis and Crystal Structure of (PPh4)3[Re2NCl10] The rhenium(V) nitrido complex (PPh4)3[Re2NCl10] ( 1 ) is obtained from the reaction of (PPh4)[ReNCl4] with 1, 3‐dioxan‐(2‐ylmethyl)diphenyl phosphine in CH2Cl2/CH3CN in form of orange red crystals with the composition 1 ·2CH2Cl2 crystallizing in the triclinic space group P1¯ with a = 1210.7(2), b = 1232.5(1), c = 2756.3(5) pm, α = 99.68(1)°, β = 100.24(1)°, γ = 98.59(1)° and Z = 2. The crystal structure contains two symmetry independent, centrosymmetrical complex anions [Re2NCl10]3‐ with a symmetrical nitrido bridge Re=N=Re and distances Re(1) ‐ N(1) = 181.34(5) and Re(2) ‐ N(2) = 181.51(4) pm. 相似文献
99.
Summary The virial theorem for a molecule in the relativistic clamped-nuclei approximation is derived. The individual energy contributionsA (momentum energy),B (mass energy),T=A+B (kinetic energy) andV (potential energy) are expressed in terms ofE, E/R (derivate w.r.t. the nuclear coordinates) and the relativistic correction E/2 (derivative w.r.t. Sommerfield's fine-structure constant ). IfE and E/R are known as functions of , then all individual energy terms are also known as functions of . As an example, numerical results for H
2
+
are presented. The relativistic and nonrelativistic potential energy curves and the paradoxical behavior of their different contributions are analyzed and interpreted in both the largeR and shortR ranges.Dedicated to Professor W. Kutzelnigg on the occasion of his 60th birthday 相似文献
100.
Joseph Schwarz Detlef Schrder Helmut Schwarz Christoph Heinemann Jan Hruk 《Helvetica chimica acta》1996,79(4):1110-1120
State-of-the-art ab initio studies demonstrate that the reaction Pd+ + CH3I → PdCH2I+ + H. is endothermic by ca. 20 kcal/mol, which translates into a bond dissociation energy (BDE) of ca. 83 kcal/mol for the Pd+? CH2I bond. This figure is in agreement with an experimental bracket of 68 kcal/mol < BDE(Pd+? CH2I) < 92 kcal/mol. Based on these findings, the previously studied Pd+/CH3I system was re-investigated, and double-resonance experiments demonstrate that the formation of PdCH2I+ occurs stepwise via PdCH as a reactive intermediate. Further, ion/molecule reactions of PdCH2I+ with unsaturated hydrocarbons are studied, which reveal the formation of carbon–carbon bonds in the gas phase. 相似文献