ELECTRON-IMPACT MASS-SPECTRA OF POLYCYCLIC AROMATIC-COMPOUNDS WITH SEVERAL TYPES OF PYRIDINOBENZANTHRONE AND BENZOBENZANTHRONE SKELETONS

Electron impact mass spectra were measured for five isomers of pyridin obenzanthrones and three isomers of benzobenzanthrones. The fragmentat ion pattern and intensity of M2+, [M-H]+, [M-CO]i+, [M - CO - H(or 2H) ]i+ and [M - CO - HCN]i+ (i = 1, 2) ions indicated remarkable differen ces and very interesting features according to the isomers with or wit hout nitrogen and condensation positions of a pyridino or benzo ring t o the benzanthrone skeleton. Further, the competition of decomposition s through [M - H]+, [M - CO]+. or [M - HCN]+. ions was confirmed by th e observation of metastable ions and the appearance energies of fragme nt ions. Interesting observations from these results were expulsion of an H atom in close proximity to the area around an O=C group, a weak bonding interaction between sp2 C-H and an O=C group, inducing specifi c hydrogen rearrangement, and characteristic charge localization on he teroatoms.