Phosphorus-nitrogen compounds: Part 66. Syntheses, structural and chiral properties of multiheterocyclic cis and trans bis (benzylspiro-N/N) cyclotriphosphazenes

In the present study, dichloro trans-(7, 8 and 9) and cis-(10, 11 and 12) bis(benzylspiroN/N)cyclotriphosphazenes were prepared by the reaction of hexachlorocyclotriphosphazene, N3P3Cl6 (HCCP; trimer) with the corresponding diamines (1, 2 and 3). The reactions of 7, 9 and 10 with excess pyrrolidine yielded trans-(13 and 14) and cis-(15) geminal-phosphazenes. Cis-derivatives (10, 11, 12 and 15) are to be in the meso form (RS/SR). Since the two benzyl groups are in the trans position in compounds 7, 8, 9, 13 and 14, they are only expected to be in the form of a racemic mixture (RR/SS). The space groups of 7 and 13 were found to be P 2(1)/n and P 2(1)/c, respectively. These two space groups are centrosymmetric and both enantiomers must exist in the crystal lattices of the compounds. Since the absolute configurations of enantiomers of 7 and 13 are respectively found as RR and SS by X-ray crystallography, the others must be SS and RR. The chiralities of 7 and 13 were also confirmed using P-31 NMR spectroscopy recorded upon the addition of chiral solvating agent [(S)-(+)-2,2,2-trifluoro-1-(9'-anthryl)ethanol, CSA]. In addition, Hirshfeld surface (HS) analysis indicated van der Waals interactions as leading intermolecular interactions in the crystal structures. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, a series of heterocyclic phosphazene compounds were synthesized by reacting different diamines with hexachlorocyclotriphosphazene, and their spatial configurations and chiral properties were further investigated. The experimental results showed that these compounds exhibit different spatial centrosymmetricity and chiral configurations.