An answer to the spiro versus ansa dilemma in cyclophosphazenes

Structural investigations of phosphorus–nitrogen compounds. 6. Relationships between molecular parameters in per-X-substituted bridged spermine derivatives and basicity constants ΣαR of substituents

“…It is known that substituent basicity constants give a reliable indication of the relative electronreleasing capacity of different substituent X groups (Feakins et al, 1965;Feakins, Last et al, 1969; and it was found that changes in bond lengths and angles of the series of cyclophosphazene derivatives (1a)±(1e) varied with the sum of the substituent basicity constants AE R (Bes Ëli et al, 2002). A similar analysis is made for (2b)±(2g) in this work and the results are compared with those for (2a) (Labarre et al, 1984).…”

“…Conformation corresponds to the syn or anti conformation of the cyclophosphazene rings about the NCH 2 CH 2 CH 2 CH 2 N bridge. Values of molecular parameters for (2a) are taken from Labarre et al (1984). Figure 5 The molecular structure of compound (2f).…”

“…Compounds (2b), (2c), (2e) and (2f) were synthesized by reaction of the known compound (2a) (Labarre et al, 1984) with an excess of the appropriate nucleophile (phenol, 1,3-propanediol, aniline and pyrrolidine, respectively), whereas The molecular structure of (2b). Criterion for observed re¯ections Mixture of independent and constrained re®nement…”

“…1 The data for (2a) were extracted from the Cambridge Structural Database (Allen et al, 1983) as a CIF, with the refcode COPTUW (Labarre et al, 1984). The molecular structure of (2d) with the benzene solvate molecule removed for clarity.…”

Formation of novel spiro, spiroansa and dispiroansa derivatives of cyclotetraphosphazene from the reactions of polyfunctional amines with octachlorocyclotetraphosphazatetraene

“…19,20 Although, a large number of octachlorocyclotetraphosphazatetraene (1), N 4 P 4 Cl 8 , with monofunctional amines were prepared and studied, 21-31 discussion on a substitution with polyfunctional amines is relatively limited in the literature. [32][33][34][35][36][37] We report here, the synthesis and structural characterization of six new cyclotetraphosphazene derivatives (scheme 1) and, to the best of our knowledge, there is no report so far of any derivative in this series that has been structurally characterized by any spectral data or x-ray crystallography.…”