Studies of Dihalogen Radical Anion Formation from Maleic Acid-Acene Compounds by Negative Chemical Ionization (NCI) and Time-of-Flight Mass Spectrometry (TOFMS)

摘要

The fragmentation characteristics of six different dichloro- and dibromo-maleic acid anhydride -acene adducts have been investigated to determine how the number of aromatic rings in the acene affects the abundance of (Cl_2)~- and (Br_2)~- fragment ions observed in the NCI-TOFMS spectra. As the number of linear fused rings in the acene group decreases, the abundance of the dihalogen radical anions is seen to increase. DFT and molecular mechanics calculations suggest the lowest energy pathway to a dichloro radical anion proceeds through a transition state where the DCMA group is coplanar with the anthracene ring system.