Simple modification of a commercial mass spectrometer for metastable data collection

Collision‐induced dissociation of negative ions in the gas phase: [Aryl S]−, [aryl SO]− and [aryl SO2]−

“…We have recently reversed the geometry of our Hitachi RMU 7D spectrometer by interchanging the source and electron multiplier by the method described by Wachs et a1. 4 and Bowie et al' and are thus in a position to determine the CID MIKE spectrum of any negative ion using the automatic scanning facility of our electric sector. 6 In this paper we address three questions, viz: (i) What are the basic collision-induced fragmentations of thiophenoxide and substituted thiophenoxide negative ions?…”

The unimolecular chemistry of [1,2‐propanediol]+˙: a rationale in terms of hydrogen‐bridged radical cations

“…First a number of reasonable mechanistic restrictions were imposed. It is clear from the literaturez9 that 1,2-and 1,3-hydrogen shifts are generally energy-demanding processes; a recent theoretical study by Yates and Radom on barriers for hydrogen shifts in ionized alkylamines indicated the following order (kJ mol-') for 1,n hydrogen shifts: 162(1,2), 132(1,3), 57(1,4) and 9 (1,5).29 Hydrogenbridged structures are very rigid towards bending of the bridge and so for such species even higher values may Therefore 1,2-and 1,3-hydrogen shifts will be avoided. For example the critical energy of H 2 0 loss from [1,2-propanediol]+' is only 16 kJ mol-' and although labelling experiments (see below) can be interpreted on the basis of a 1,3-hydrogen shift to produce [CH,=C(OH)CH,] +' + H 2 0 this possibility will be treated with reserve.…”

Steric courses of chemical reactions. II

“…Although the symbols for the cyclic and dihedral permutation groups are the same as the symbols for their isomorphic point groups, their intended significance should be clear from context. (7) In calculating group orders, the following relations are of help: Here, i?¡ww is a representation of the full point group of a molecule having geometry i. We can generate the permutation group R, from a slightly different point of view which will be useful below.…”

“…Also, the group of allowed permutations is H = Si + S¡ + Si +S3. If the configurations shown in Figure la are defined to be reference configurations, thus defining the labeling of skeletal positions, then the operation /z,vv = (1 )(234)(5)(6) (7) (8)vv is a permutational isomerization reaction since htYY E HYY is not an operation in VYY. If, however, we assume "free" rotation about the A1-C5 bond in configurations having geometry V, i.e., such internal motion is immeasurably rapid on the observational time scale, then hfY E HYY does not represent observable stereochemical change.…”