New cis-(4-6) and trans-dispirocyclic ferrocenylphosphazene derivatives (7-9) were obtained by reactions of hexachlorocyclotriphosphazene (N3P3Cl6) with N-alkyl-N-monoferrocenyldiamines of the formula FcCH(2)NH(CH2)(n)NHR [n = 2, R = CH3 (1); n = 2, R = C2H5 (2) and n = 3, R = CH3 (3)]. Characterizations of the products were performed using MS, FTIR, H-1, C-13 and P-31 NMR techniques. The crystal structures of 5 (with 8), 6, 7 and 9 were determined by X-ray crystallography. The most important result of this study was that the trans chiral phosphazenes crystallized as only one enantiomer. Studies of the antibacterial and antifungal activity of the phosphazenes (4-9) showed that compounds 6 and 7 were effective against P. vulgaris and K. pneumoniae. The cytotoxic activities of 4-9 against L929 fibroblasts and DLD-1 colon cancer cells were investigated. The necrotic effects of 4 and 7 were greater in the DLD-1 cell line than those in the L929 cell line. DFT calculations were carried out using the B3LYP functional with the LANL2DZ basis set to determine the energies, the orientations of the molecular orbitals (HOMOs and LUMOs) and the molecular electrostatic potential (MEP) surfaces of the partly substituted cyclotriphos-phazenes (6, 7 and 9). The results for 6, 7 and 9 revealed that these bonded to the active sites of A-DNA and B-DNA by weak non-covalent interactions, which was also supported by molecular docking investigations.