Several 6-substituted 6, 7-dihydro-5H-dibenzo [d, f][1, 3, 2] diazaphosphepine 6-oxides have been synthesized and their structures were confirmed by IR and mass spectra. The existence of hydrogen bonding between the amidic hydrogens and the phosphoryl oxygen in theses compounds is indicated by the IR spectra. Under electron impact, the splitting pattern of these compounds takes about four major fragmentation pathways. The stability ...