Unexpected second-order effects in proton-coupled 13C NMR spectra

‘Unexpected’ second-order effects encountered in proton-coupled ¹³C NMR spectra where relative proton shifts are large compared to proton-proton coupling constants are illustrated. The observed phenomenon is explained, with reference to the ABX spin system as a model, as being due to the near equality of the relative proton shift, in frequency units, to the difference between one-bond and long-range ¹³CH couplings. The effect may be removed by a change in operating field strength or addition of a shift reagent.     

RecognizingG-induced flows

A flow on a homogeneous space need not come from the action of a one-parameter subgroup of the ambient transitive group. We exhibit an inductive method for determining when this is the case.     

Anchimeric assistance in electron-impact reactions: Homoallylic systems

A combination of a kinetic approach, thermochemical approach and atomic labeling techniques has been employed to demonstrate that several series of allylic and homoallylic bromides undergo Br· expulsion with the aid of remote π-electron density.     

Neutron scattering study of 49 K phase transition in TTF-TCNQ

Elastic neutron scattering measurements show the existence of three low temperature phase transitions in TTF-TCNQ and are interpreted within the framework of a recent theoretical investigation by Bak and Emery. Direct evidence for the new 49 K transition is presented in addition to the 38 and 54 K transitions reported previously.