696-86-6Relevant articles and documents
Ring Inversion in 1,4,7-Cyclononatriene (Trishomobenzene). Force-Field Calculation for Abnormally Large Bond Angles
Anet, Frank A. L.,Ghiaci, Mehran
, p. 2528 - 2533 (1980)
The barrier to ring inversion in 1,4,7-cyclononatriene has been measured by 1H dynamic NMR spectroscopy in tetrachloroethylene, 1,1,2,2-tetrachloroethane, and toluene-d8 as solvents.Values of ΔG near room temperature vary from 14.5 +/- 0.1 to 14.8 +/- 0.1 kcal/mol.Values of ΔS vary from -2.2 +/- 2 to -4.9 +/- 2 eu and are not strongly negative (-18.2 +/- 0.1 eu in CDCl3), as previously reported.Values of ΔH vary from 13.1 +/- 0.5 to 14.1 +/- 0.5 kcal/mol.Calculations with the Boyd force field show that the strain energy of the crown conformation is 4.6 kcal/mol lower than that of the saddle conformation.The barrier for ring inversion is not well reproduced by the calculations, and possible reasons for this are discussed.