Models for intramolecular exchange in organic pi-conjugated open-shell systems: a comparison of three non-kekule biphenyldinitrenes

The cryogenic matrix photolysis of diazide precursors that were expected to produce biphenyl-3,4'-dinitrene (1), biphenyl-3,3'-dinitrene (2) and biphenyl-4,4'-dinitrene (3), was used to analyze the major influence of connectivity on the nature of intramolecular exchange coupling of unpaired electrons by the biphenyl group. The findings related to dinitrenes 1 to 3, when compared with those connected with dicarbene molecules, revealed that the electron exchange coupling patterns of dinitrenes and dicarbenes are similar.