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

A combined mass‐spectrometric and theoretical approach has been used for an investigation of the gas‐phase chemistry of two representative alkylperoxy anions. Metastable CH 3 OO − 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,H 3 ,O 2 − and [C,H,O 2 ] ‐ potential‐energy surfaces at the BECKE3LYP/6‐311+ + G ** level of theory. Upon exhaustive methylation of the α‐position as in t ‐C 4 H 9 OO − anions, the reactivity switches completely to an elimination of (CH 3 ) 2 CCH 2 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 ‐C 4 H 9 OOLi) 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 ‐C 4 H 9 OOLi subunit on the oxenoid oxygen atom of a second t ‐C 4 H 9 OOOLi moiety. This reaction may produce t ‐C 4 H 9 OOOLi trioxy species as intermediates, which rapidly decompose to singlet dioxygen and t ‐C 4 H 9 OLi.