Coles, S. J., Davies, D. B., Hursthouse, M. B., Ibisoglu, H., Kilic, A. and Shaw, R. A.
Conformational polymorphism in a chiral spiro-cis-ansa-bridged cyclotriphosphazene derivative
Acta Crystallographica Section C Crystal Structure Communications, C58, (1), . (doi:10.1107/S010827010101770X).
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The reaction of spermidine with 2,2,4,4-tetrachloro-6,6-diphenylcyclotriphosphazene produces a mixture of products of which one of the fractions is a spiro-cis-ansa derivative, namely 12-chloro-14,14-diphenyl-2,6,11,13,15,16-hexaaza-1,12-diphosphatricyclo[ 10.3.1.0(1,6)]hexadeca-12,14-diene, C19H26ClN6P3. Recrystallization of this fraction from different solvents results in the formation of two different crystalline forms. The rod morphology formed in dichloromethane-n-hexane (1:1) produces a triclinic structure with three molecules in the asymmetric unit. These three molecules adopt different conformations as a result of two NH groups flipping in an ansa-bridged ring system. The plate morphology crystals, grown in dichloromethane-n-hexane-ethyl acetate (1:1:1), produce a C-centred monoclinic structure that adopts a conformation that is essentially the same as one of the forms in the triclinic structure.
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