Differing fragmentation of boron chelates of aromatic azo compounds confirms the structural formulae 1a-7c, presented in [2].More significant differences are caused by the substituent of the boron R (F instead of C6H5).Although certain rules can be deduced by the substitution of F for CeHs with regard to the change in intensity of the ions M+, M+-R (and others), in some cases the stable aromatic azo system causes a significant change in the fragmentation as compared with that of azomethine chelates. The chelates 7 eliminate “RH” and show no molecular ion. Apparently a second chelate ring is closed before further fragmentation can start. Fragmentation of 7 a and b is analogous to 5.
IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man. Volume 8: Some Aromatic Azo Compounds