Mass Spectrometric Study of [Fe,C 3 ,H 6 ,O] + Isomers Relevant in the Gas‐phase Oxidation of Hydrocarbons by “Bare” FeO +

The structures and energetics of [Fe,C 3 ,H 6 ,O] + isomers are probed by mass spectrometric means. The complexes Fe‐(CH 3 COCH 3 ) + , Fe(CH 3 CH 2 CHO) + , Fe(CH 3 OCH=CH 2 ) + , Fe(CH 2 O)(C 2 H 4 ) + , c ‐(FeOCH 2 CH 2 CH 2 ) + , Fe(CH 2 =CH‐CH 2 OH) + , and Fe(OH)(C 3 H 5 ) + can be distinguished by comparing their reactivity toward benzene and their collision‐induced dissociation mass spectra, respectively. These findings are used to interpret the formation of [Fe,C 3 ,H 6 ,O] + in oxidation reactions of hydrocarbons by the highly reactive FeO + cation. For example, in the reactions of FeO + with norbornane and pentanol Fe(OH)(C 3 H 5 ) + is produced, while the reaction of FeO + with norbornane to yield [Fe,C 3 ,H 6 ,O] + is one of the rare cases of initial CC bond activation by a “bare” transition‐metal oxide. The reaction of FeO + with propene involves formation of metalla oxetanes as primary products. In general, “bare” FeO + is not selective and allylic CH bond activation of propene competes efficiently, thus pointing to a potentially rich chemistry.