Bimolecular Gas‐Phase Reactions of d‐Block Transition‐Metal Cations With Dimethyl Peroxide: Trends Across the Periodic Table

Abstract

AbstractThe bimolecular gas‐phase reactions of d‐block transition‐metal cations M+ with dimethyl peroxide were screened by means of Fourier transform ion cyclotron resonance mass spectrometry. The rich chemistry can be classified into four types of reactions: i) Oxygen‐atom transfer to generate MO+, ii) elimination of radicals, mostly CH3O˙, iii) intramolecular redox reaction of dimethyl peroxide to form CH3OH, CH2O and CO, and iv) charge transfer from the metal cation to produce CH3OOCH3+. Some general trends became apparent from this study. For example, the “early” transition metals almost exclusively induce oxygen transfer to generate MO+, in line with the notoriously high oxophilicities of these metals, and electron transfer is only observed for Zn+ and Hg+. Both the radical loss and the disproportionation reaction emerge from a rovibrationally highly excited insertion intermediate (CH3O)2M+, and for the first‐row metals the branching ratio of the competing processes seems to be affected by the M+OR bond strengths as well as the electronic groundstate configurations of M+. For the 4d and 5d cations Ru+Ag+ and Pt+Au+, respectively, products resulting from intramolecular redox reactions dominate; this probably reflects the higher propensity of these metal ions to facilitate β‐hydrogen atom shifts.