Anions [N(CH2)3]− and [ON(CH2)2]− are Stable in the Gas Phase, but Can They Be Charge Stripped to Form the Radicals N(CH2)3 and ON(CH2)2? A Joint Experimental and Theoretical Study

Collision-induced activation of deprotonated trimethylamine N-oxide yields the two anions [N(CH2)3]– and [ON(CH2)2]– following losses of H2O and CH4, respectively. These two anions decompose by minor losses of H• and H2 when collisionally activated: no other fragmentations are noted. Calculations at the CCSD(T)/aug-cc-pVDZ//B3LYP/6-31+G(d) level of theory indicate that these trigonal anions are stable, and should not rearrange following collisional activation. Collisional-induced charge stripping of the anions [N(CH2)3]– and [ON(CH2)2]–, respectively, form N(CH2)3 and ON(CH2)2. Some of these neutrals are energised and undergo rearrangement and dissociation. From a consideration of experiment and theory, it is proposed (i) that energised N(CH2)3 may cyclise to form the 1-aziridinylcarbinyl radical. This species may ring open to CH2=NCH2CH2 which then decomposes to CH2N and C2H4 and (ii) energised ON(CH2)2 may undergo OC cyclisation followed by ring opening to energised CH2=NCH2O which may fragment to yield CH2N and CH2O.