Crystal structures of three hexakis-(fluoroar-yloxy)cyclo-triphosphazenes.

ABSTRACT: The syntheses and crystal structures of three cyclo-triphosphazenes, all with fluorinated ar-yloxy side groups that generate different steric characteristics, viz. hexa-kis-(penta-fluoro-phen-oxy)cyclo-triphosphazene, N3P3(OC6F5)6, 1, hexa-kis-[4-(tri-fluoro-methyl)-phen-oxy]cyclo-triphosphazene, N3P3[OC6H4(CF3)]6, 2 and hexa-kis-[3,5-bis(-tri-fluoro-methyl)-phen-oxy]cyclo-triphosphazene, N3P3[OC6H3(CF3)2]6 3, are reported. Specifically, each phospho-rus atom bears either two penta-fluoro-phen-oxy, 4-tri-fluoro-methyl-phen-oxy, or 3,5-tri-fluoro-methyl-phen-oxy groups. The central six-membered phosphazene rings display envelope pucker conformations in each case, albeit to varying degrees. The maximum displacement of the 'flap atom' from the plane through the other ring atoms [0.308?(5)?Å] is seen in 1, in a mol-ecule that is devoid of hydrogen atoms and which exhibits a 'wind-swept' look with all the aromatic rings displaced in the same direction. In 3 an intra-molecular C-H(aromatic)?F inter-action is observed. All the -CF3 groups in 2 and 3 exhibit positional disorder over two rotated orientations in close to statistical ratios. The extended structures of 2 and 3 are consolidated by C-H?F inter-actions of two kinds: (a) linear chains, and (b) cyclic between mol-ecules related by inversion centers. In both 1 and 3, one of the six substituted phenyl rings has a parallel-displaced aromatic ?-? stacking inter-action with its respective symmetry mate with slippage values of 2.2?Å in 1 and 1.0?Å in 3. None of the structures reported here have solvent voids that could lead to clathrate formation.

SUBMITTER: Yennawar HP 

PROVIDER: S-EPMC6775729 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature