Crystal structures of three hexakis­(fluoroar­yloxy)cyclo­triphosphazenes

摘要

The syntheses and crystal structures of three cyclo­triphosphazenes, all with fluorinated ar­yloxy side groups that generate different steric characteristics, viz. hexa­kis­(penta­fluoro­phen­oxy)cyclo­triphosphazene, N3P3(OC6F5)6, >1, hexa­kis­[4-(tri­fluoro­methyl)­phen­oxy]cyclo­triphosphazene, N3P3[OC6H4(CF3)]6, >2 and hexa­kis­[3,5-bis(­tri­fluoro­methyl)­phen­oxy]cyclo­triphosphazene, N3P3[OC6H3(CF3)₂]₆ >3, are reported. Specifically, each phospho­rus atom bears either two penta­fluoro­phen­oxy, 4-tri­fluoro­methyl­phen­oxy, or 3,5-tri­fluoro­methyl­phen­oxy 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 mol­ecule 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 intra­molecular C—H(aromatic)⋯F inter­action 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 inter­actions of two kinds: (a) linear chains, and (b) cyclic between mol­ecules related by inversion centers. In both >1 and >3, one of the six substituted phenyl rings has a parallel-displaced aromatic π–π stacking inter­action 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.