Four-centre skeletal rearrangements in the mass spectra of thioanilides

Abundant peaks in the mass spectra of thioanilides involve loss of a substituted thiophenoxy radical by a process involving aryl migration from nitrogen to sulfur (a four-centre skeletal rearrangement). The effects of substituents on this process have been studied. Substituents in the amide ring, in the acid part of the molecule and on the nitrogen atom were studied. Four-centre aryl migrations seem to be favoured if the aryl group migrates from one atom to either a more polarizable or a more electronegative atom, and in the case of thioanilides this migration is more important in tertiary compounds than in secondary compounds.     

Local realist model for the coincidence rates in atomic-cascade experiments

We assume that the two photons emerging from an atomic cascade process are classical wave-packets with well defined intensities and states of elliptical polarization. Such weak light signals, when interacting with optical devices such as linear polarizers and quarter-wave plates, are assumed to undergo stochastic changes of intensity in addition to the change in polarization experienced by macroscopic signals. We show how such assumptions can lead, in a natural way, to an enhancement in the detection probability of certain signals, and hence to a family of models which fit the observed counting rates in all atomic-cascade experiments so far performed, including those which investigate the circular polarizations of the photons.     

Die Kristallstruktur von 2,5-Diäthyl-7-(1-methyl-2-imidazolyl)-1H-pyrrolo[3,4-c]pyridin-1,3,6 (2H, 5H)-trion

The crystal structure of the title compound was determined by an X-ray analysis. The solution proceeded via the Faltmolekel method and the refinement with 1140 significant structure factors led to R = 0.060 for 262 structural parameters.     

Kristalline und molekulare Struktur von N-Isopropyl-7endo-phenyl-5,9-methano-6,7,8,9-tetrahydro-5 H-benzo-cyclohepten-6exo-yl-amin

Crystal and Molecular Structure of N-Isopropyl-7endo-phenyl-5,9-methano-6,7,8,9-tetrahydrobenzocyclo-hepten-6exo-yl-amin The structure of the title compound was determined by X-ray analysis of its hydrochloride. Space group Iba2, a=32.58, b=15.55, c=7.30 Å. The structure was refined by LS-methods with 718 significant data to R=0.053.     

Template Synthesis,Crystal Structure,and Spectroscopic Characterization of [N,N′-Bis(2-pyridylmethylene)-1,3-diamino-2-methyl-2-nitropropane] copper(II) Perchlorate

In a facile carbon-acid condensation reaction of bis(2-aminomethylpyridine)copper(II) with nitroethane and formaldehyde in basic MeOH the N,N′-bis(2-pyridylmethylene)-1,3-(diamino-2-methyl-2-nitropropane)copper(II) cation is produced in essentially quantitative yield. The perchlorate salt crystallizes in space group P2₁en, a = 9.083(2), b = 15.198(3), c = 16.025(3). Cu(II) is essentially four-coordinate, though there are weak axial interactions to the perchlorate O-atoms. There is a large tetrahedral distortion from the least-squares plane through the Cu and four N donors; with the Cu(II) in the plane, N-atoms are up to 0.25 Å above or below. Solution spectroscopy confirms that the solution structure of the cation is qualitatively the same as in the solid. The complex and its precursor have been investigated by room-temperature magnetic-moment measurement, voltammetry, and by IR, electronic, and electron spin resonance spectroscopy.     

An abnormal fries rearrangement induced by a peri-methoxyl group in monoacetates of naphthohydroquinones.

The acetyl group of two 1-acetoxy-4-hydroxy-5-methoxynaphthalenes migrates to C-3 on treatment with boron trifluoride etherate.     

Modulating Electron Transfer in a Simple Bichromophoric System Employing Axial-Ligation as an Organising Precept

A naphthalene diimide acceptor 1 bearing a pyridine group linked directly (a series) or through a —CH₂CH₂— spacer (b series) coordinated axially to a metallotetraarylporphyrin (MP) undergoes fast photoinduced electron transfer (in the case of MP = Zn(II)TTP) while the kinetically more stable ruthenium complexes (MP = Ru(CO)TPP) have been used to illustrate the correlation between the distance of probe protons from the porphyrin plane and the change in chemical shift (Δδ) upon coordination. Changes in the emission spectra at 650 nm (λ _ex= 400 nm) upon the addition of Zn(II) ions and/or 1b to TTPH₂ can be interpreted in a truth table to illustrate a NAND gate.     

Networks

The Computational Perspective

Networks