Low-lying excited states and photodissociation studies of cis-BrONO

A computational study of the low-lying singlet and triplet states of bromine nitrite, cis-BrONO, is presented. Calculations of excitation energies and oscillator strengths are reported using multi-reference configuration interaction, MRD-CI, methods in conjunction with the cc-pVDZ?+?sp and cc-pVTZ?+?sp basis sets. In agreement with recent experimental work the calculations find two important transitions, namely to the states 2¹ A′ at 3.99?eV and 4¹ A′ at 5.27?eV. The corresponding measurements obtained 3.87 and 5.44?eV, respectively. Both states show multi-reference character, representing a linear combination of 3a″?→?4a″ and 9a′?→?10a′ transitions. The potential energy curves for the Br+ONO dissociation are repulsive for both states indicating possible photodissociation. BrO+NO products are not favoured because the corresponding potential energy curves show barriers on the order of 0.5?eV.     

Engineering students designing a statistical procedure for quantifying variability

The study examined first-year engineering students’ responses to a statistics task that asked them to generate a procedure for quantifying variability in a data set from an engineering context. Teams used technological tools to perform computations, and their final product was a ranking procedure. The students could use any statistical measures, and they needed to explain their ranking procedure in detail. The responses were first categorized by the statistical measures used. The responses were categorized using a cyclic model development perspective moving from primitive to more sophisticated responses. The modeling cycle framework provided a developmental view of students’ responses and use of statistics. The study raised questions related to the measurement of variability, the application of statistics, and the process teams go through when designing an analysis procedure.     

Synthesis of new benzo[h]‐ and benzo[f]chromeno[2,3‐b]‐pyridine‐5‐ones

A number of new benzo[h]‐ and benzo[f]chromeno[2,3‐b] pyridine‐5‐ones derivatives were synthesized from benzo[h]‐ and benzo[f]‐chromone‐carbonitriles and amino‐benzo[h]‐ and benzo[f]chromone‐carbaldehydes. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:2–7, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20152     

Potential dependence of step and kink energies on Au(100) electrodes in sulfuric acid

Using electrochemical STM we studied monolayer high Au islands on Au(100) electrodes in sulfuric acid as a function of the electrode potential. We made use of theoretical and experimental methods recently developed for UHV experiments on metal islands. It is demonstrated that these models are likewise applicable to islands on metal electrodes in a liquid environment. From a quantitative analysis of the equilibrium island shape and of the island shape fluctuations we determined the step free energy (line tension) as a function of orientation and the kink energy, and the dependence of these quantities on the electrode potential. In a first approach to a theoretical understanding the electrostatic contributions to the line tension are considered. It is concluded that these contributions should add significantly to the observed variation with the potential. This fails however to provide essential features of the experimental result.     

TiOBr; Darstellung,Eigenschaften und Struktur*

TiOBr was prepared by reaction of Ti with TiO₂ and Br₂. The compound forms fiat reddish-brown needles and shows a temperature independent weak paramagnetism. It crystallises in the orthorhombic system (Pmmn; a = 3.787, b = 3.487, c = 8.529 Å) with the FeOCl type of structure. The interatomic distances are Ti?O = 1.952; 2.245 Å (2X) and Ti?Br = 2.544 Å (2X).     

Das Problem der körperfesten Achsen bei Systemen mit gleichen Teilchen

The suitable choice of a body-fixed frame of reference (BFR) is an essential point in the treatment of systems with identical particles. Starting from the fact that there exists a “best” BFR (“specific decoupling”), in which the wave function is a product of an internal and a collective part, we show that the collective term has to be invariant under permutations of the particles. On the other side in symmetrical configurations the BFR has to jump in a well-defined manner under those permutations which are equivalent to spatial rotations. It is shown that for non-symmetrical configurations the BFR must have the same properties. For 3 identical particles it is possible to construct in a purely geometrical way a BFR which has the right behaviour under particle permutations. The Hamiltonian in that BFR is derived and the connection with the “best” BFR is discussed.     

Novel multidentate sulfur-nitrogen ligands with enhanced complexation properties

Di(tert-butyl)sulfur diimide and bis(trimethylsilyl)sulfur diimide were reacted with different metalated amines to form versatile novel multidentate ligand systems with side-arm donation. Their complexation properties in terms of ligand design, denticity and the cation size are discussed. We report herein the synthesis and structure elucidation of [(tBuN)(2)S{LiMe(2)N(C(6)H(4))S(NtBu)(2)}(2)] (1), [(Li{Me(2)N(C(6)H(4))S(NSiMe(3))(2)})(2)] (2), [(Li(thf){Me(2)N(C(6)H(4))S(NSiMe(3))(2)})(2)] (3), [(Li{2-PicS(NSiMe(3))(2)})(2)] (4), [(Li{Me(2)N(CH(2))(2)N(Me)S(NSiMe(3))(2)})(2)] (5), [(Na{Me(2)N(CH(2))(2)N(Me)S(NSiMe(3))(2)})(2)] (6) and [(K{Me(2)N(C(6)H(4))S(NSiMe(3))(2)})(2)] (7).     

Peroxide solvation by a toroidal lithium inverse crown ether complex assembled by multidentate polyimido sulfonates

In this communication we present the synthesis of the inverse crown ether complex [Li(2)O(2)·Li(4){CH(2)(N(Me)CH(2)S(NtBu)(2))(2)}(2)] (1) which is able to accommodate peroxide in a torus of lithium ions.