Synthesis, structural, and stereogenic characterizations of new trispirocyclotriphosphazenes
Yasemin Tümer
Abstract
Abstract In this study, trispirophosphazenes containing biphenyl‐2,2′‐dioxy and ferrocenyldiamino groups were synthesized to investigate their stereogenic and structural properties. For this purpose, monospiro ( 1 ) and trans/cis‐dispiro ( 2 and 3 ) cyclotriphosphazenes were obtained from the reactions of hexachlorocyclotriphosphazatriene (N 3 P 3 Cl 6 ; trimer; HCCP ) with N ‐ethyl‐ N ′‐ferrocenylmethyl‐ethylenediamine. Subsequently, bis(biphenyl‐2,2′‐dioxy)‐substituted ferrocenylphosphazene ( 4 ) was prepared from the reaction of an equimolar amount of monoferroceylphosphazene ( 1 ) with two equimolar amounts of dipotassium biphenyl‐2,2′‐dioxide. Reactions of equimolar amounts of 2 and 3 with equimolar amounts of dipotassium biphenyl‐2,2′‐dioxide yielded trans‐( 5 ) and cis‐( 6 ) trispirophosphazenes, respectively. Characterizations of all trispiro compounds were made using 1 H, 13 C, and 31 P NMR spectra. In addition, trispirophosphazenes 5 and 6 have two equivalent stereogenic P‐centers. Trans ‐ 5 and cis ‐ 6 are expected to exist in racemate and meso forms. The molecular and crystal structures of the two phosphazenes ( 4 and 5 ) were clarified by single‐crystal X‐ray crystallography. Also, since the absolute configuration of one enantiomer of 5 is found to be RR, the other must be SS.