On the Oxenoid Character of Alkylperoxy Anions and Their Lithium Compounds: A Combined Mass‐Spectrometric and Theoretical Investigation

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Abstract
A combined mass‐spectrometric and theoretical approach has been used for an investigation of the gas‐phase chemistry of two representative alkylperoxy anions. Metastable CH3OO− ions undergo unimolecular loss of molecular hydrogen and formaldehyde yielding HCO−2 and OH−, respectively. The observed reactivity is in pleasing agreement with calculations of the [C,H3,O2− and [C,H,O2]‐ potential‐energy surfaces at the BECKE3LYP/6‐311+ + G** level of theory. Upon exhaustive methylation of the α‐position as in t‐C4H9OO− anions, the reactivity switches completely to an elimination of (CH3)2CCH2 giving rise to the formation of HOO−. The results obtained for the “bare” alkylperoxy anions are used for the analysis of the EI mass spectrum of (t‐C4H9OOLi)12 dodecamers, which thermally decompose in the inlet system at a probe temperature of ca. 130°C. The decomposition is rationalized by a mechanism involving nucleophilic attack of one t‐C4H9OOLi subunit on the oxenoid oxygen atom of a second t‐C4H9OOOLi moiety. This reaction may produce t‐C4H9OOOLi trioxy species as intermediates, which rapidly decompose to singlet dioxygen and t‐C4H9OLi.

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