The Cl exchange reactions of hexachlorocyclotriphosphazene, N3P3Cl6, with two equimolar amounts of N-alkyl-N'-mono(4-fluorobenzyl)diamines (1-3), FC6H4CH2NH(CH2)(n)NHR1 (n=2 and 3, R-1=CH3 or C2H5), and N-alkyl-N'-mono(4-nitrobenzyl)diamines (4 and 5), NO2C6H4CH2NH(CH2)(n)NHR1 (n= 2, R-1= CH3 or C2H5), led to the formation of the mono(4-fluorobenzyl) (1a-3a) and mono(4-nitrobenzyl) (4a and 5a) spirocyclotriphosphazenes as minor products, and trans-bis(4-fluorobenzyl) (1b-3b) and trans-bis(4-nitrobenzyl) (4b and 5b) spirocyclotriphosphazenes as major products. The bis(4-fluorobenzyl) spirocyclotriphosphazene (1b) reacted with excess pyrrolidine to give fully substituted (1c) phosphazene. The structures of the new compounds were elucidated by elemental analyses, ESI-MS, FTIR, H-1, C-13, and P-31 NMR techniques. The molecular and crystal structures of 1a, 3b and 6 were identified by single crystal X-ray crystallography. The absolute configurations of 3b and 6 were unambiguously established as SS and R respectively, using X-ray crystallographic data. On the other hand, the interactions of 1b, 1c, 3b-5b and 6 with plasmid DNA indicated that compounds 3b, 4b, and 5b caused a decrease in the mobilities and intensities of form I and form II DNA. Compounds 1b, 1c and 6 caused a double strand break of plasmid DNA. All of the tested compounds inhibited enzyme cleavage indicating compound bindings to the specific G/G and A/A nucleotides.