Synthesis and nuclear magnetic resonance spectroscopy of geometrical isomers of 1,3,5-trimethyl-2,4,6-tris(p-methylphenoxy)-2,4,6-trioxocyclotriphosphazane: X-ray crystal structure of the trans isomer
Abstract
Both cis and trans isomers of tri(N-methyl)tris(p-methylphenoxy)trioxocyclotriphosphazane, N3Me3P3O3(OC6H4Me-p)3, have been prepared by the thermal rearrangement of the respective trimethoxycyclophosphazenes, N3P3(OC6H4Me-p)3(OMe)3. The crystal and molecular structure of the trans isomer has been determined; it crystallises in the P space group with a= 8.444(1), b= 11.753(1), c= 14.196(1)Å, α= 97.408(8), β= 92.487(10), γ= 102.325(10)°, and Z= 2. The structure has been solved by direct methods and refined to a R value of 0.060. The six-membered N3P3 phosphazane ring adopts a twist–boat confirmation. The structural data have been used to explain the n.m.r. spectroscopic features. A chair conformation is proposed for cis-N3Me3P3O3-(OC6H4Me-p)3 on the basis of n.m.r. data.