Structural investigation of the new potent DNA alkylator spiro(2H-1,3,2-benzodiazaphosphole-2,2',lambda 5 [1,3,5,2,4,6] triazatriphosphorine),4',4',6',6'-tetrakis(1-aziridinyl)-1,3,4',4',6', 6',-hexahydro.

The molecular structure of spiro(2H-1,3,2-benzodiazaphosphole-2,2',lambda 5 [1,3,5,2,4,6] triazatriphosphorine), 4',4',6',6'-tetrakis(1-aziridinyl)-1,3,4',4',6',6'-hexahydro (CAS 133586-94-4), a recently synthesized potent cytostatic, was determined using X-ray diffraction method. The substance crystallizes in P2(1)2(1)2(1) orthorhombic space group. The unit cell contains 8 formal molecules coupled into 4 pseudo-centrosymmetric dimers by double intermolecular hydrogen bonds. The compound revealed, besides previously determined long-term chemical stability and good water solubility, also radiation stability. In spite of having less aziridinyl groups than 1,3,5,2,4,6-triazatriphosphorine,2,2,4,4,6,6-hexakis (1-aziridinyl)-2,2,4,4,6,6-hexahydro (N3P3Az3, Az = aziridinyl, CAS 52-46-0; Myko 63) the compound is twice more cytostatically active. Hypotheses attributing high cytostatic activity to the existence of conjugated pi-electron systems in the molecule and dimeric structures are discussed.