The mass spectra of the
zinc(11) and nickel(11) chelates of four fluorinated monothio-β-diketones,
RC(SH)=CHCOCF3 (R = Ph, p-MeC6H4,
2-thienyl, Me), have been obtained. The mass spectra of the nickel chelates
have considerably more peaks due to metal-containing species than the spectra
of the zinc chelates, while the reverse is true for the metal-free fragments.
All the zinc chelates give peaks for M (molecular ion), M ? CF3, M -
L (LH = monothio-β-diketone), M - L ? CF2,
LH, L, L - F, RCSCH and RCS. All the nickel chelates give peaks for M, M - F, M
? CF3, M - COCF3, M - L, M- 2L and L. In addition, some of the
metal chelates give other peaks. Mechanisms are proposed for the reactions
giving rise to some of these species. All the zinc and nickel chelates give a
strong peak due to L+ arising from a valence change of the metal ion
from the bivalent to the univalent state as follows: [Me11L2]+
→ L+ + Me1L (Me = Zn, Ni). It is suggested that the
ion L+ has a resonance-stabilized cyclic structure.