Metastable ion characteristics. XXIV. Application of collisional activation spectra to the elucidation of organic ion structures

Abstract

Perhaps a better interpretation of the reduction properties, however, is one that places the added electrons in a ligand * MO of bm symmetry (Figure 7).The bathochromic shift of the M -L (b3g -* Ltt*) transition in the electronic spectra of the adducts and the energy of this transition relative to that of the d-d transition62 suggest that, in the adducts, the ligand * MO of bm symmetry is of lower energy than the dxy metal orbital. The per cent metal character of the (52) From the reported by Carlin and Canziani63 for Co(Dto)a3t he energy of the transition for the Ni(Dto)z2_ is calculated to occur at 17,700 cm-1. A shoulder found at 17,700 cm-1 in the spectrum of Ni(Dto)z2_ has been assigned43 to the transition. In agreement with the stronger M-S bonding in the adducts is the fact that, in the adducts, larger values of are generally observed.64 (53) R. L. Carlin and F. Canziani, J. Chem. Phys., 40,371 (1964). ( 54) D. Coucouvanis and D. Piltingsrud, J. Amer. Chem. Soc., in press.bm MO cannot be ascertained, although the reduction properties of the adducts and the stability of the reduction products clearly depend66 on the type of metal atom bonded to the -diketone portion of the coordinated dithiooxalate ligand and to a lesser extent on the environment about this atom.

Extensive rearrangement reactions observed for differently N-substituted 2,5-dimethylpyrroles under electron ionization

“…The fourteen molecules can be divided into three groups according to the substituent at position one: hydroxyalkyl substituted (1-4), aminoalkyl substituted (5-11) and alkyl substituted (12)(13)(14) pyrroles.…”

“…When comparing the CID spectra of different ions it has to be kept in mind that the intensity of the peaks related to the processes of lowest activation energy may depend on the internal energy of the ion. 13 Because the ions studied were collisionally cooled before isolation the CID spectra were not corrected for the lowest energy processes. Exact mass measurements were made in broad band mode using perfluorotributylamine (PFTBA) as external standard.…”

A Century of Progress in Molecular Mass Spectrometry

“…[At that time, CI was a common abbreviation for chemical ionization; currently, the terms CID and collision-activated dissociation (CAD, my preference) are used interchangeably to designate the technique.] Subsequent studies established the fundamentals of the technique (74) and illustrated its broad applications (75). It became possible to characterize the full structure of a larger molecule through CAD identification of its individual fragment ions (76).…”

Metastable ion studies. VI. The identification of C2H5N+• ion structures from their characteristic kinetic energy releases

“…Finally, ion structure (e) has no oxy-analogue. It has been proposed that such ions are generated from N-methylpiperidine (4, 5) and trimethylamine (2).…”

“…It is isoelectronic with C2H4O+' and in view of the similarity with which oxygen and nitrogen atoms direct mass spectral decompositions, we were interested to see whether the analogous nitrogencontaining ions are stable. Such an analogy certainly exists between the C2H50+ and C2H6N+ ions which have been subject to several investigations (2,3). The C2H5N+ ion, although an important fragment ion in the mass spectra of many nitrogen-containing compounds, has only been investigated by conventional labelling studies (4)(5)(6).…”