Formation of neutral C7H2 isomers from pour isomeric C7H2 radical anion precursors in the gas phase

Consideration of theoretical calculations [E3LYP/aug-cc-pVDZ//B3LYP/6-31G(d )] of the structures of ten C7H2 neutral isomers and the nine corresponding C7H2 radical anions have led us to synthesize four stable C7H2 radical ani ons in the ion source of our ZAB 2HF mass spectrometer, and to convert thes e to C7H2 neutrals. The four radical anion isomers prepared were (i) [(HC e quivalent to C)(2)C=C=C](-.) [from the reaction between (HC equivalent to C )(3)COCH3 and HO- ], (ii) [HC=C=C=C=C=C=CH](-.) [from the reaction between HC equivalent to C-C equivalent to C-CD(OH)-C equivalent to CH and HO-], (i ii) [C=C=C=C=C=C=CH2](-.) [from the reaction between DC equivalent to C-C e quivalent to C-C equivalent to C-CH2OCH2CH3 and HO-], and (iv) [C equivalen t to C-CH2-C equivalent to C-C equivalent to C](-.) [from the bis desilylat ion reaction of (CH3)(3)Si-C equivalent to C-CH2-C equivalent to C-C equiva lent to C-Si (CH3)(3)With SF6-.]. The four anions were further characterize d by their collisional activation (negative ion) and charge reversal (CR, p ositive ion) mass spectra. The anions were converted into their correspondi ng neutrals by charge stripping, and the correspondence between the charge reversal (CR) and neutralization reionization (-NR+) mass spectra of each a nion is taken as evidence that within the time frame of the -NR+ experiment (some 10(-6) s), each neutral is stable and undergoes no major rearrangeme nt or interconversion to a more stable isomer. Theory and experiment are in accord for these systems.