Seven new diphosphorus heterocyclic compounds 2,4,5-diazadiphospholanes I (R = H, alkyl, halo, MeO, Me2N) were prepared by cyclocondensation of Me2CHNHP(O)(OEt)CONHMe with 4-RC6H4PCl2 followed by oxidation with DMSO. The existence of cis- and trans-isomers in these compounds was proved by 31P NMR and GC-MS.

Key words: INFRARED SPECTROPHOTOMETRY, MASS SPECTROGRAPHY, NMR SPECTROMETRY, NITROGEN HETEROCYCLICS, PROTON MAGNETIC RESONANCE SPECTROMETRY, ISOMER, PHOSPHOROUS HETEROCYCLIC COMPOUNDS, CYCLOPENTANE