Phosphorus-nitrogen compounds: Part 43. Syntheses, spectroscopic characterizations and antimicrobial activities of cis- and trans-N/O dispirocyclotriphosphazenes containing ferrocenyl pendant arms

The cis- (5 and 6) and trans-dispiroferrocenylphosphazenes (7 and 8) containing ferrocenyl pendant arms were synthesized from the reactions of hexachlorocyclotriphosphazene, N3P3Cl6, with two equimolar amounts of the sodium salts of the ligands; [2-(N-ferrocenylmethylamino)-1-ethanoxide (1) and 3-(N-ferrocenylmethylamino)-1-propanoxide (2)]. The monospiroferrocenylcyclotriphosphazenes (3 and 4) were also isolated from the reaction mixtures as by-products. The characterizations of the new compounds (5–8) were elucidated using MS, FTIR and 1H, 13C and 31P NMR techniques. The molecular structure of 6 was established by X-ray crystallography. As expected, compounds 5, 6, 7 and 8 have two stereogenic P-atoms. The compounds 5 and 6 are likely to be in cis (meso) forms, whereas the compounds 7 and 8 are in trans (racemic) forms. Besides, the antimicrobial activities of the cyclotriphosphazenes against G(+) and G(−) bacteria and fungi were evaluated. The interactions of the compounds with pBR322 plasmid DNA were also investigated.