Reaction pathways of Sc⁺ (³D, ¹D) and Fe⁺ (⁶D, ⁴F) with acetone in the gas phase: metal ion oxidation and acetone deethanization

Abstract

The reactions of Sc(+) ((3)D, (1)D) and Fe(+) ((6)D, (4)F) with acetone have been investigated in both high- and low-spin states using density functional theory. Our calculations have indicated that oxidation of Sc(+) by acetone can take place by (1) metal-mediated H migration, (2) direct methyl-H shift and/or (3) C=O insertion. The most energetically favorable pathway is metal-mediated H migration followed by intramolecular ScO(+) rotation and dissociation. For the deethanization of acetone mediated by Fe(+), the reaction occurs on either the quartet or sextet surfaces through five elementary steps, i.e. encounter complexation, C-C bond activation, methyl migration, C-C coupling and non-reactive dissociation. The rate-determining step along the quartet-state potential-energy surface (PES) is similar to that in the case of Ni(+) ((2)F, 3d(9)), namely the methyl-migration step. For the sextet-state PES, however, the energy barrier for methyl migration is lower than that for C-C bond activation, and the rate-determining step is C-C coupling. In general, the low-spin-state pathways are lower in energy than the high-spin-state pathways; therefore, the reaction pathways for the oxidation of Sc(+) and the Fe(+)-mediated deethanization of acetone mostly involve the low-spin states.

Theoretical study of Ni+ assisted C C and C H bond activations of propionaldehyde in the gas phase

“…On the contrary, transition metal ions with high oxygen affinities react with acetone to form MO + ions and C 3 H 6 , e.g. Sc + , V + , Ti + , Gd + and Pr + [21], [22]. The reactions of transition metal ions with acetaldehyde found that decarbonylation of acetaldehyde by Fe + , Co + , Cr + , Ni + is a dominant process at low reaction energies.…”