Röntgenstrukturanalyse des 1,3-Bis(diethylamino)-1,3-dibenzyl-2,4-diphenyl-1λ5, 3λ5-diphosphets

X-Ray Crystal Structure Determination of 1,3-Bis(diethylamino)-1,3-dibenzyl-2,4-diphenyl-1λ⁵, 3λ⁵-diphosphete Benzylidene-diethylamino-benzylfuorophosphorane, 1 , reacts with lithium bis(trimethylsilyl)amide to give the title compounds 2 and 1-diethylamino-2,3-diphenylphosphirane, 3 . Only one of the stereoisomers of 2 is formed in which the two benzyl groups are located on the same side of the planar four-membered ring. 2 crystallizes in the monoclinic space group P2₁/n.     

The Vlasov dynamics and its fluctuations in the 1/N limit of interacting classical particles

For classicalN-particle systems with pair interactionN ^–1 ø(q _i–q _i) the Vlasov dynamics is shown to be thew*-limit asN. Propagation of molecular chaos holds in this limit, and the fluctuations of intensive observables converge to a Gaussian stochastic process.     

The polarized electronic spectra and electric field spectra of benzo-diazoles. II. 2,1,3-benzothiadiazole

The S₁ ← S₀ absorption spectra of 2,1,3-benzothiadiazole (BTD) have been measured at 4.2 K in four different host crystals: naphthalene, durene, p-dichlorobenzene (DCB) and p-dibromobenzene. Detailed vibrational analyses are given for BTD imbedded in napthalene and DCB. The polarization measurements show that the S₁ state has B₂ symmetry, like its selenium analogue (BSD). The transition is dominated by a single totally symmetric mode - 484 cm^?1. The Herzberg-Teller coupling contributes only a very small fraction of the total intensity. The Stark measurements of a DCB sample containing both BTD and BSD enabled us to compare the charge distribution of BTD and BSD in the state S₁. The Stark splittings of BTD are 17% greater than the splittings of BSD. Reorganization of the σ-core during the excitation is used to explain the difference. The drastic change in dipole moment upon excitation implies that the S₁←S₀ transitions of BTD and BSD are not localized in the six-membered ring as suggested by previous workers. Weak phosphorescence of BTD in napthalene and DCB and singlet-triplet absorption spectrum of neat BTD have been observed. The heavy atom effect of spin-orbit coupling is to explain the ST absorption intensity of BTD and BSD.     

Routes to unique palladium A-frame complexes with a bridging fluoro-ligand

Treatment of a toluene solution of [PdMe(2)(Cy(2)PCH(2)PCy(2))](1) with pentafluoropyridine in the presence of traces of water affords the generation of the A-frame complexes [(PdMe)(2){mu-kappa(2)(P,P)Cy(2)PCH(2)PCy(2)}(2)(mu-F)][SiMeF(4)]() and [(PdMe)(2){mu-kappa(2)(P,P)Cy(2)PCH(2)PCy(2)}(2)(mu-F)][OC(5)NF(4)](2b). If the reaction is performed in an NMR tube equipped with a PFA inliner, complex 2b is produced, only. Treatment of 1 with pentafluoropyridine in the presence of an excess water yields the pyridyloxy complex [PdMe(OC(5)NF(4))(Cy(2)PCH(2)PCy(2))](3). Compound [(PdMe)(2){mu-kappa(2)(P,P)Cy(2)PCH(2)PCy(2)}(2)(mu-F)][FHF](2c) bearing a bifluoride anion instead of SiMeF(4)(-) or OC(5)NF(4)(-) can be generated by reaction of 1 with substoichiometric amounts of Et(3)N.3HF. The analogous complex [(PdMe)(2){mu-kappa(2)(P,P)Ph(2)PCH(2)PPh(2)}(2)(mu-F)][FHF] (5c) has been synthesized by addition of Ph(2)PCH(2)PPh(2) to a solution of [PdMe(2)(Me(2)NCH(2)CH(2)NMe(2))](4) in THF and subsequent treatment of the reaction mixture with Et(3)N.3HF. The structure of the A-frame complex 5c has been determined by X-ray crystallography.     

Über Oxostannate(II). III. K2Sn2O3, Rb2Sn2O3 und Cs2Sn2O3 – ein Vergleich

On Oxostannates(II). III. K₂Sn₂0₃, Rb₂Sn₂0₃, and Cs₂Sn₂O₃ – a Comparison Hitherto unknown Rb₂Sn₂O₃ has been obtained by heating of mixtures of binary oxides [RbO_0.48 + SnO, Rb:Sn = 1.1:1, Al₂O₃?cylinders, Ar] as deep yellow powder or deep yellow single crystals. It is isotypic to K₂Sn₂O₃, R3 m-D with a = 6.086 Å, c = 15.101 Å, Z = 3, d_calc = 4.69, d_obs = 4.64 g X cm^?3. For 260 hkl it is R = 5.2₇% and R_w = 5.0₉% (MoKα, 4-circle diffractometer data). The structure of K₂Sn₂O₃ and Rb₂Sn₂O₃ is compared with that of Cs₂Sn₂O₃. For both types Effektive Coordination Numbers, ECoN, and the Madelung Part of Lattice Energy, MAPLE, have been calculated.     

Error analysis for complex kinetics systems methyl-vinyl cross-radical reactions

Many rate constants, particularly for radical-radical reactions, are determined in systems exhibiting complex kinetics. Parameters often comprise several species concentrations, absorption cross sections, and rate constants. They cannot be obtained from an exact analytic expression, and therefore, must be solved iteratively through an efficient numerical differential equation solver. We examine here the reaction kinetics of the CH₃ and the C₂H₃ mixed-radical system, generated by excimer laser photolysis of methyl vinyl ketone (MVK) at 193.3 nm. As a model, a detailed error analysis for determination of the cross-radical reaction rate constant, the initial CH₃ and C₂H₃ radical concentrations are performed using a least-squares modeling program (Acufit). The least-squares program, an assumed mechanism, a detailed set of signal-averaged data, are viewed as the measuring “instrument.” The output of the “instrument” consists of a “signal” that is fit to the data using the least-squares criterion. This gives estimated parameters that are examined with respect to random as well as systematic errors. The biases due to uncertainties of each known parameter and combined uncertainties on the measured parameters are assessed. © 1994 John Wiley & Sons, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Flash photolysis resonance fluorescence study of the reaction Cl + O3 → ClO + O2 over the temperature range 213–298 K

Rate constants for the removal of Cl atoms in the reaction Cl + O₃ → ClO + O₂ were measured by the flash photolysis resonance fluorescence technique over the temperature range 213–298 K. The rate constant is given by the Arrhenius expression (2.94 ± 0.49) × 10^?11 exp[?(298 ± 39)/T] in units of cm³ molecule^?1 s^?1. Comparison with recent results from other laboratories are presented.